Chemical composition of wheat and rye flour. nutritional value and composition of flour composition and nutritional value of flour

Examination of flour quality.

Purpose of work: assessment of the quality of wheat and rye flour.

Flour is a powdered product with a different granulometric composition, obtained by grinding (grinding) grain. Flour is used for the production of bakery, confectionery and pasta products.

Flour is divided into types, types and varieties.

Types of flour differ depending on the culture from which it is developed. So, flour can be wheat, rye, corn, soy, barley, etc. Wheat flour is the most important, accounting for 84% of the total flour production.

flour type are distinguished within the type of flour, depending on the intended purpose. So, wheat flour can be bakery, for pasta, confectionery, ready for consumption (cooking), etc. In the production of a certain type of flour, grain with the necessary physical, chemical and biochemical properties is selected. For example, for the production of pasta flour, durum or high-glass soft wheat is taken and flour is obtained, consisting of relatively large homogeneous endosperm particles. In the production of baking flour, soft glassy or semi-glassy wheat is used and finely ground flour is obtained, from which it is easy to make soft, moderately elastic dough, to obtain a high yield of lush, porous bread.

Rye flour is produced in only one type - baking.

Flour grade distinguished within each type. The division into varieties is based on the quantitative ratio of endosperm and shell particles. Flour of the highest grades consists of particles only of the endosperm. Inferior grades contain a significant amount of shell particles. Varieties differ in chemical composition, color, technological advantages, calorie content, digestibility, biological value (Table 2.1).

Table 2.1. The chemical composition of wheat flour of different varieties

Content per 100 g of product	Flour grade
higher	first	second	wallpaper
Water, g	14,0	14,0	14,0	14,0
Proteins, g	10,3	10,6	11,7	11,5
Fats, g	1,1	1,3	1,8	2,2
Mono- and disaccharides, g	0,2	0,5	0,9	1,0
Starch, g	68,7	67,1	62,8	55,8
Fiber, g	0,1	0,2	0,6	1,9
Ash, g	0,5	0,7	1,1	1,5
Minerals, mg
Na
To
Sa
mg
R
Fe	1,2	2,1	3,9	4,7
Vitamins, mgyo
β-carotene		Traces	0,01	0,01
IN 1	0,17	0,25	0,37	0,41
IN 2	0,04	0,08	0,12	0,15
RR	1,20	2,20	4,55	5,50

Nutritional value of wheat flour. Wheat flour of all types and varieties has some common properties due to the properties of the grain of wheat. These include the characteristic features of proteins, carbohydrates, enzymes and other substances that make up wheat flour, as well as the structure of cells, starch grains, etc.

Wheat flour proteins mainly consist of insoluble hydrophilic proteins - glutenin and gliadin (in ratios 1:1.2; 1:1.6). Other proteins (albumins, globulins, nucleoproteins) are contained in small amounts, mainly in low-grade flour. The most important property of glutenin and gliadin is the ability to form an elastic mass - gluten - in the process of swelling. The yield of raw gluten when washed from flour of different varieties is 20 - 40%, and the share of dry matter accounts for about 1/3 of the mass of raw gluten. The composition of dry gluten includes (%): protein -5 - 9, carbohydrates - 8 - 10, fat and fat-like substances - 2.4 - 2.8, minerals - 0.9-2.0.

During kneading, gluten forms a continuous phase of wheat dough, retains carbon dioxide during fermentation, thereby ensuring good leavening of the dough, and during baking, gluten denatures, coagulates, releasing excess water, and fixes the porous structure of bread. In the production of pasta, due to the presence of gluten, wheat dough has high plasticity and cohesion, and it is possible to produce pasta of various shapes. When drying pasta, gluten hardens, fixes the shape of the pasta and determines their glassy consistency.

For the quality of flour, not only the amount of gluten is important, but also its elasticity, resilience and extensibility.

Carbohydrates in wheat flour are mainly represented by starch. Its amount fluctuates between 65 - 80%. Wheat starch, if it consists of whole, undamaged grains, swells well, gives a viscous, slowly aging glue erased. Starch during saccharification is a source of sugars used in the fermentation of the dough.

The sugars of benign wheat flour are mostly represented by sucrose - 2-4% and to a lesser extent by directly reducing sugars (maltose, glucose and fructose) - 0.1-0.5%. The amount of sugar is an important factor in the baking qualities of flour. Due to the fact that the sugars contained in wheat flour are not enough for fermentation, the activity of flour saccharifying enzymes is of great importance. The process of sugar formation proceeds in flour from high-grade grain according to the scheme: starch - glucose and fructose phosphates - sucrose - invert sugar. In flour from defective grains (self-heating, sprouted), starch is hydrolyzed mainly under the action of the enzymes amylase and maltase with the formation of a significant amount of dextrins, maltose and glucose, therefore, such flour is characterized by a markedly increased content of dextrins and directly reducing sugars.

Wheat flour, especially low grades, is an important source of minerals (Ca, Fe, P and some trace elements) and water-soluble vitamins (B l B 2 , PP). The content of ballast substances - fiber and pentosans is small and depends on the type of flour: in the highest grades, the amount of fiber is 0.1 - 0.15%, pentosans - 1 - 0.15; in the lowest - 1.6 - 2 and 7 - 8%, respectively.

Nutritional value and properties of rye flour largely due to the chemical and tissue composition of rye grain, the properties of its constituent substances. A distinctive feature of rye flour is the presence in its composition of a large amount of water-soluble substances (13-18%), including soluble proteins, carbohydrates, and mucus. Rye flour contains slightly less proteins than wheat flour - an average of 10 - 14% (Table 2.2).

Table 2.2. The chemical composition of rye flour

Content, mg/100 g of product	Flour grade
seeded	peeling	wallpaper
Water	14,0	14,0	14,0
Squirrels	6,9	8,9	10,7
Fats	1,4	1,7	1,9
Mono- and disaccharides	0,7	0,9	1,1
Starch	63,6	59,3	55,7
Cellulose	0,5	1,2	1,8
Ash	0,6	1,2	1,6
Minerals:
Na
To
Sa
mg
R
Fe	2,9	3,5	4,1
Vitamins:
β-carotene	Traces	Traces	0,01
IN 1	0,17	0,35	0,42
IN 2	0,04	0,13	0,15
RR	0,99	1,02	1,16

Under normal conditions, rye flour proteins do not form gluten, which can be separated from other substances. The so-called intermediate protein is capable of forming a certain amount of gluten, but this is of no practical importance, since gluten is not washed off from rye flour. Rye flour proteins contain water- and salt-soluble fractions capable of unlimited swelling. The total amount of soluble and soluble proteins reaches 50-52% of their total content; with soluble carbohydrates and mucus, they form viscous colloidal solutions that make up the continuous phase of rye dough.

Rye flour proteins have a favorable amino acid composition; compared to wheat flour proteins, they are relatively rich in amino acids such as lysine, histidine, valine, leucine.

The amino acid tyrosine is involved in enzymatic oxidation and the formation of dark-colored substances - melanins. For this reason, and also due to the interaction of amino acids with reducing sugars and the formation of melanoidins, rye flour of all varieties gives a darkening dough and bread with a dark crumb and crust.

Carbohydrates make up 80 - 85% of the dry mass of flour and are represented by starch, sugars, pentosans, mucus and fiber.

Starch in rye flour, depending on its variety, contains from 60 to 73.5%. For the most part, it consists of large lenticular-shaped grains. Rye starch has the lowest gelatinization temperature (46 - 62 ° C) and the ability to produce a viscous, slowly aging paste. This property, combined with the overall high content of soluble substances, results in a soft texture and slow staleness of rye bread.

Sugars in rye flour are in the amount of 6 - 9%. They contain few reducing sugars - 0.20 - 0.40%, represented by glucose and fructose, a lot of sucrose - 4 - 6% of the mass of flour (or 80% of all sugars), as well as maltose, raffinose and trifructosans.

Fiber in rye flour, despite the presence of a relatively large number of shell particles (there are 20–26% in wholemeal flour), is about the same as in wheat flour (0.4–2.1%, depending on the variety). This is due to a significantly lower fiber content in the shells and aleurone layer of rye.

A feature of rye flour is the presence of pectin substances, the amount of which is higher than in wheat flour (Table 2.2).

Fat - there is little of it in rye flour - 1 - 2%. Linoleic (43%), palmitic (27%), oleic (20%) acids predominate in its composition, there is linolenic acid (4%); also contains lecithin (9% of fat mass) and tocopherols - vitamin E (258 mg%), which are natural antioxidants, so rye flour fat is highly resistant to rancidity. Coloring substances of flour are represented by flavone pigments, anthocyanins and chlorophyll.

Quality expertise flour is produced according to the following indicators: organoleptic, technical, physico-chemical and technological. General quality indicators characterize the freshness and good quality of flour - color, smell and taste.

flour color mainly due to its type and variety, i.e. the color of the grain and the content of endosperm and bran particles in the flour. It is determined visually in a dry or wet sample or analytically - using special instruments - photoanalyzers.

Flour of each type and grade has its own color: grits - cream, wheat flour of the highest grade - white, the first - white with a yellowish tint, the second - white with a clear brownish tint, wallpaper - with a darker brownish tint, seeded rye - white, slightly bluish, peeled rye and wallpaper - white with a distinct gray or brownish tinge, etc. Abnormal changes in the color of flour can be caused by an increased content of bran, improper grinding of flour, the presence of impurities (maryannik, smut, etc.) that give the flour unusual dark shades, as well as its spoilage and the formation of dark-colored substances (melanoidins) in it.

The smell of flour usually determined in a small (5 - 10 g) amount of flour slightly heated by breathing. Fresh flour has a specific mild pleasant smell. There is no mustiness, moldy smell and any foreign smell. The appearance of an odor that is not characteristic of normal flour can be caused by various reasons: rancidity of fat, the development of penicillium fungi, and other molds (aspergillus, mucor, etc.). In addition, musty and moldy odors result from the adsorption of odorous substances when flour is stored in damp, poorly ventilated areas. Foreign odors (wormwood, garlic, sweet clover) can be caused by the ingress of the corresponding odorous impurities into the flour, the adsorption of odorous substances when packing flour in dirty containers, as well as during storage in warehouses or transportation in wagons with foreign odors.

Taste determined by chewing a small (2 - 3 g) amount of flour Benign flour has a mild pleasant, slightly sweet taste. Flour should not have a sour, bitter or clearly sweet taste, as well as the presence of foreign flavors. Changes in taste can be caused by spoilage of flour (sourness or rancidity), the production of flour from defective grains. Spoiled grain gives a sour or bitter taste, sprouted - sweet, foreign impurities - wormwood, mustard, briar. Flour of any kind, when chewed, should not give a crunchy feeling on the teeth. The crunch is caused by the ingestion of crushed mineral impurities into the flour.

The indicators determined by analytical methods include moisture content, ash content, grinding fineness.

Humidity, i.e. the amount of free and physically bound water, expressed as a percentage of the mass of the product. Usually, flour made from high-quality grain and stored under favorable conditions has a moisture content in the range of 13-15%. The increased humidity of flour, which occurs in cases of processing substandard grain, improper conduct of the technological process (washing and conditioning of grain) or as a result of storing flour in conditions of high relative humidity (above 70-75%), adversely affects the quality of flour. At high humidity, free water accumulates in it, activating the activity of enzymes and contributing to the rapid development of microflora, which sharply reduces the shelf life and often leads to spoilage of flour. In addition, the increased moisture content of flour significantly affects the properties of proteins and starch, reduces its ability to swell and impairs baking properties.

Quantity and quality of raw gluten determined to characterize the baking or pasta properties of wheat flour. This indicator is provided in the standards and quality norms for flour.

Gluten is a protein jelly that remains after washing the dough with water and removing starch, fiber and water-soluble substances from it. The gluten-forming proteins are concentrated in the peripheral parts of the endosperm; therefore, less gluten is formed in the premium flour than in flour of grades I and II. It should be borne in mind that raw gluten contains from 60 to 75% water and its yield depends not only on the protein content in the flour, but also on its ability to absorb and retain more or less water. If the gluten is dried and weighed, it is possible to determine the content of dry gluten, and by the ratio of the mass of raw gluten to the dry mass, its water absorption capacity. For gluten of normal quality, this value is 2.5 - 3%.

For wheat flour of different types and grades, limit norms for the yield of raw gluten (%, not less than) are established: for baking flour: semolina - 30, premium - 28, first - 30, second - 25, wallpaper - 20; for pasta flour from durum wheat - 30 - 32, from soft - 28 - 30.

The washed gluten is evaluated organoleptically by color (light, dark), elasticity and extensibility.

According to the current standard for test methods, flour gluten, like grain gluten, is divided into three groups:

I - good - elastic, normally extensible (up to 10 cm or more);

II - satisfactory - less elastic, different extensibility;

III - unsatisfactory - low-elasticity, strongly stretching, spreading, crumbling.

Gluten in bread flour should be of good or satisfactory quality, and pasta flour should be of good quality.

Unsatisfactory in quality is recognized gluten, which spreads when in water. The gluten of this group is usually dark gray or brownish in color.

Ash content in terms of dry matter, it serves as an indirect indicator of the varietal affiliation of flour of all kinds.

The determination of the flour grade by its ash content is based on the uneven distribution of minerals in the tissues of cereal grains. For wheat (on average), mineral substances (%) are distributed as follows: ash content of the endosperm - 0.4, aleurone layer - 10, shells - 4, germ - 5; for rye: ash content of endosperm - 0.5, aleurone layer - 6.7, shells - 3.7, germ - 4.5. Therefore, the highest grade flour has an ash content of 0.4-0.6%, and as the grade decreases and the number of bran particles increases, the ash content increases, reaching an ash content in wholemeal flour close to the ash content of the whole grain (1.9 - 2%).

Grinding size determined in a sample isolated from an average sample weighing 50 g. To determine the fineness, sieves are selected that are established by regulatory documents for the corresponding type of product.

A sample of the product is poured onto the upper sieve, covered with a lid, a set of sieves is fixed on the sieving platform and the sieving is switched on. After 8 minutes, the sifting is stopped, the sieve shells are tapped, and sieving is continued again for 2 minutes. At the end of sieving, the remainder of the upper sieve and the passage of the lower sieve are weighed and calculated as a percentage of the mass of the sample taken.

The fineness of grinding determined and normalized in this way gives only an approximate idea of ​​the degree of grinding of the product. Current regulations limit the amount of coarse particles and guarantee a known minimum of fine particles. Norms for all types and grades, except for grains and pasta flour, the degree of flour grinding is not limited. The passage through any thick sieve can be increased to 100%, and the particle sizes are reduced to a high degree of dispersion. Therefore, different grades of flour - the highest, the first, the second - in terms of the degree of grinding in some cases differ little from each other.

Different grain size of flour is closely related to its properties - water absorption and sugar-forming ability, swelling ability and other indicators. Grain and pasta flour is characterized by a reduced water absorption capacity, slowly swells and is capable of additional swelling. This process consists in the fact that when kneading the dough, substances swell on the surface of relatively large particles and, with a small amount of water used, a cohesive dough is formed, but then the moisture is absorbed by the internal colloidal system of particles and the consistency of the dough changes. The dough becomes more cohesive and dense. Coarse flour has a lower sugar-forming capacity. Such flour is best used for the production of pasta, where the minimum water absorption capacity, as well as the ability of the dough to additional swelling, makes it easier and cheaper to obtain high-quality pasta.

For baking flour, increased fineness is undesirable, since the yield of bread, except for some rich products, decreases, the process of dough formation slows down, bread from it is obtained in a small volume and with a coarser porosity.

Bread flour for retail trade has the best properties if it consists of sufficiently small (70-100 microns) homogeneous particles with a grainy structure. Such flour has a sufficiently high water absorption capacity, the dough from it is elastic, well retaining its elastic properties. Sugar-forming ability is also close to optimal.

Heavily crushed (dusty and ground) flour has undesirable properties: an excessively large water absorption capacity (the dough from it quickly liquefies, the bread is reduced in volume, with a dense, often crumbly crumb and a dark crust). Hearth bread made from such flour usually turns out vague. The fraying of flour has a particularly strong effect on its enzymatic activity. Mechanically damaged starch grains are subject to more rapid action of enzymes, which causes its rapid liquefaction and saccharification. Such starch is saccharified several times faster than normal medium grains.

The content of the metal-magnetic impurity in flour is limited by special regulations. Metal particles get into the flour in the form of grains of slag, ore, rust in case of poor grain cleaning or unsanitary condition of the mill. Particles of cast iron and steel get into the product as a result of wear of rollers, steel screens, metal gravity flows. Most of the metal is extracted in mills using magnetic devices installed along the path of the product, but a small part of it remains in the flour. The amount of magnetic impurities in flour is determined by extracting the metal from a 1 kg flour sample. The metal is extracted using strong magnets - magnetic horseshoes or on a special apparatus - a ferroanalyzer. The isolated metal impurity is weighed on an analytical balance. In flour, more than 3 mg of metal-magnetic impurities per 1 kg of flour are not allowed. The size of individual particles of a metal-magnetic impurity in the largest linear dimension should not exceed 0.3 mm, and the mass of individual particles should not exceed 0.4 mg.

The content of harmful and grain impurities in flour is also normalized, but determined by analyzing the grain before grinding. The results of grain analysis are indicated in the documents on the quality of flour and flour is evaluated on them. The following limiting standards for the content of impurities (%) have been established: ergot, smut, mustard, briar - no more than 0.05, including mustard and briar - no more than 0.04; the admixture of heliotrope pubescent and trichodesma incanum is absolutely not allowed; cockle seeds - no more than 0.1; grains of barley, rye (in wheat) and germinated - no more than 4 in total, including germinated grains, the number of which is determined in the grain before cleaning - no more than 3.

Flour with a high content of harmful impurities is unsuitable for human consumption. Grain impurities, especially barley and sprouted grains, reduce the baking properties of wheat and rye flour.

Infestation of flour by pests(beetles and their larvae, butterflies and their caterpillars, as well as ticks) is not allowed according to the current rules and regulations.

To establish the infection, 1 kg of flour is sifted through sieves (varietal flour through a sieve No. 056, and wallpaper flour through two sieves No. 067 and 056). The passage through the No. 056 sieve is used to detect mites, and the residues on the No. 056 and 067 sieves are used to detect other pests, scattering the residue in a thin layer on the analysis board and carefully examining it.

Ticks in flour are difficult to distinguish and therefore they are detected indirectly. Five portions of 20 g each are taken from the flour that has passed through a sieve No. 056. Each sample is placed on the glass and lightly pressed with a piece of paper or glass to make the surface perfectly smooth. Then, after some time, the surface of the pressed flour is carefully examined. The appearance of swellings or grooves indicates the presence of mites.

Bulk yield and dimensional stability of bread set by trial baking. It is used in the evaluation of wheat flour, less often - rye.

For baking, 1000 g of flour is usually taken at a moisture content of 14% (or the mass of flour is brought to this moisture content); when kneading the dough, use 530 - 540 ml of water, 30 g of pressed yeast and 15 g of salt. The dough ferments for 160 minutes with 1 - 2 punches at 32°C. The finished dough is divided into three equal parts. Two are placed in iron molds, and the third is molded into spherical hearth bread. The dough is proofed (at 35 0 C and relative humidity 80%) to the maximum volume. The surface of the dough is moistened with water and baked at 225 - 230 0 C for 30 minutes.

After cooling (after 4 hours), the volumetric yield of bread and the ratio of the height of the hearth bread to its diameter are established. The volume is determined in a special device consisting of a vessel of a fixed capacity and a measuring cylinder equal in volume to it, filled with flax seeds or millet. Bread is placed in the first vessel, filled with flax seeds or millet flush with the edges, the volume of bread is determined from the remainder of the seeds in the cylinder, and then divided by the mass of flour (g) spent on baking this bread, and multiplied by 100; the result is a volumetric yield of bread (cm 3) per 100 g of flour. The hearth loaf is measured by determining its diameter and height, and the ratio of height to diameter H/D is calculated. According to the volume output of panned bread and the H/D ratio of hearth bread, the baking properties of the flour are judged.

There are many different test baking methods. One of them can be cited as an example: for high-grade wheat flour, the volumetric yield of bread is from 350 (for second grade flour) to 500 cm 3 (for premium flour), and the H / D ratio is from 0.35 to 0, 5 respectively.

Baked bread is used to determine taste, smell, color, crumb structure, porosity and other indicators.

Test baking also reveals flour contaminated with potato disease. To do this, one loaf is wrapped with wet paper or cloth and left for 24 hours. Then it is cut or broken. The appearance of lumps or threads of mucus in the crumb indicates that the flour is infected with potato disease.

Baking bread from rye flour due to the need to use sourdough and multi-phase dough management is used relatively rarely. They are usually replaced with kolobok pastries: 50 g of flour is kneaded with 41 ml of water at room temperature, a ball (kolobok) is formed from the resulting dough and baked at 230 ° C for 20 minutes. Then the quality of the baked kolobok is determined. It has been established that the assessment of flour by the quality of the kolobok is quite close to its assessment by autolytic activity.

From flour of good quality with medium autolytic activity, a bun of the correct shape is baked, without noticeable cracks, with a fairly dry crumb. The content of water-soluble substances in the crumb - 23 - 28%.

Flour with reduced autolytic activity also produces a bun of regular spherical shape, but small in volume, very pale in color, with a dense and dry crumb. The content of water-soluble substances in the crumb is less than 23%.

When baking from flour with increased autolytic activity, the bun is flat, spreading, with cracks on the surface, with a sticky crumb. The content of water-soluble substances is more than 28%.

gas holding capacity- is determined simultaneously with gas-forming. It is characterized by an increase in the volume of dough during fermentation and is expressed either as a percentage of the volume of gas released, or as the ratio of the volume of fermented dough to the original volume.

Determining the gas-forming and gas-holding capacity is important. However, the results of this determination depend on many factors - yeast, test conditions, etc. In addition, the experience requires a lot of time. At the same time, the gas-forming ability of flour depends on its sugar-forming ability, and the gas-retaining ability depends on the quantity and quality of gluten and the elastic properties of the dough. For all these reasons, it is more reasonable to resort to the definition of the latter indicators.

Gas generating capacity determined in the following way: from the test flour (100 g) knead the dough with the addition of salt and yeast, place it in a cylinder and let it ferment for a certain time (5 hours) and under certain conditions (30 ° C), setting the amount of carbon dioxide released. This amount varies widely - from 1000 to 2200 ml or more.

Requirements for the quality of wheat baking and rye flour are given in table. 2.8 and 2.9 (applications).

In accordance with SanPiN 2.3.2.1078 - 01, the safety indicators for all types of flour are as follows (Table 2.3):

Table 2.3. Maximum content of hazardous substances in flour

Practical part

Laboratory analysis of flour for quality compliance with the standards of flour mills is carried out according to the scheme shown in Figure 2.1

Rice. 2.1. Scheme of flour analysis

Lesson 1. "Examination of the quality of wheat flour"

1. Determination of organoleptic indicators of flour __________________.

(type of flour)

Colour. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .________________

Smell. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .________________

Taste. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ________________

2. Determination of moisture content of flour. Humidity is determined by drying the sample. To do this, a sample of 5 g of flour is placed in a weighing bottle with a ground lid, weighed on an analytical balance, and then placed in an oven for 50 minutes at 130 ° C, after which the weighing bottle is placed in a desiccator for cooling and weighed again. Humidity is calculated by the formula:

where m 1 is the mass of an empty bottle, g;

m 2 - mass of weighing bottle with wet yeast, g;

m 3 - weight of bottle with dried yeast, g.

When calculating the results, fractions up to 0.05 are discarded, and fractions equal to 0.05 or more are rounded up to 0.1.

Moisture determination method. . . . . . . . . . . . . . . . . ________________

Weight of an empty bottle, m 1, g. . . . . . . . . . . . . . . . . . . ________________

Bulk weight in wet flour, m 2, g. . . . . . . . . . . ________________

Weight of bottle with dried flour, m 3, g. . . . . . . .________________

Moisture content of flour, W, %. . . . . . . . . . . . . . . . . . . . . . . .________________

3. Infection determined by sifting 1 kg of varietal flour through a wire sieve No. 056, wallpaper - through wire sieves No. 067 and No. 056. The residues on the sieves are analyzed for the presence of beetles, pupae, larvae. The passage of sieve No. 056 is used to determine mite infestation.

4. Grinding size of flour determined by sifting on a laboratory sieving a test portion weighing 100 g for sifting flour and 50 g for high-quality flour on sieves established by the standard. The residue on the upper sieve characterizes the presence of large particles in the flour, and the passage on the lower sieve characterizes the presence of small particles. Enter the results in table 2.5.

Table 2.4. Grinding size of flour _____________________

(type of flour)

Sieve	Residue on the sieve, g	Percentage of neither sieve, %

The result of the analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . _________________

5. Determination of baking power wheat flour on sedimentation sediment.

The determination method is based on the ability of flour protein substances to swell in weak solutions of lactic or acetic acids and form a precipitate, the value of which characterizes the amount of protein substances. In a 100 ml measuring cylinder with a ground stopper, graduated with a division value of 0.1 ml, add 3.2 g of flour, weighed on a technical scale. 50 ml of distilled water, tinted with bromophenol blue dye, is poured into the cylinder. Turn on the stopwatch (it is not stopped until the end of the definition). The cylinder is closed with a stopper and shaken for 5 s, sharply moving in a horizontal position. Get a homogeneous suspension. The cylinder is placed in a vertical position and left alone for 55 s. After removing the cork, pour 25 ml of a 6% solution of acetic acid. Close the cylinder and turn it over 4 times within 15 s, holding the stopper with your finger. Leave the cylinder alone for 45 s (up to 2 minutes by the stopwatch from the beginning of the determination). Within 30 s, the cylinder is smoothly turned over 18 times. Leave for the third time alone for exactly 5 minutes and immediately make a visual reading of the volume of sedimentation sediment to the nearest 0.1 ml. If a small part of the sediment floats, it is added to the main sediment. The established volume of sedimentation sediment (ml) is recalculated for flour moisture content of 14.5% according to the formula

where V y exp - actually measured value of sedimentation sediment, ml;

w m - actual moisture content of the studied flour, % for dry-air substance.

To assess the baking power by the amount of sedimentation sediment, the following approximate standards are recommended.

Table 2.5. Sedimentation sediment (ml) at different grinding sizes

Record in the laboratory journal:

Actual measured value of sedimentation sediment, V c.exp, g. .___________

Humidity of the studied flour, W, % . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ___________

Installed volume of sedimentation sediment, V Y, ml. . . . . . . . . . . . . ___________

6. Quantity and quality of raw gluten.

A portion of flour 25 g is weighed on technical scales and placed in a porcelain mortar or cup and 13 ml of tap water is poured at a temperature of 16 ... 20 ° C. Flour and water are mixed with a spatula, getting a dough, which is then well kneaded by hand. Dough particles adhering to the cup and spatula are carefully collected (cleaned with a knife) and attached to a piece of dough.

After rolling the dough into a ball, place it in a cup and cover with glass for 20 minutes so that the flour particles are saturated with water, the proteins swell. Then the gluten is washed from starch and shells under a weak stream of tap water over a thick silk or nylon sieve, slightly kneading the dough with your fingers. At first, washing is carried out carefully, not allowing pieces of gluten to come off together with starch and shells, after removing most of the starch and shells, more vigorously Accidentally detached pieces of gluten are collected and attached to the total mass of gluten.

It is allowed to wash gluten (if there is no running water) in a basin or container containing at least 2 liters of water. Knead the dough in water with your hands. When starch and shells accumulate in the water, it is drained, filtered through a thick silk or nylon sieve, a new portion of water is poured and so on until the end of washing, which is established by the absence of starch in the water (almost transparent), flowing down when gluten is squeezed out. If the gluten is not washed out, the results of the analysis are recorded as "Not washable".

Having finished washing the gluten, it is squeezed between the palms, which are periodically wiped dry with a towel. At the same time, the gluten is turned out several times with your fingers, each time wiping your palms with a towel. Do this until the gluten begins to slightly stick to your hands.

The gluten is weighed, washed again for 2-3 minutes, squeezed again and weighed again. The washing of gluten is considered complete when the difference in mass between two weighings is not more than 0.1 g. The amount of raw gluten is expressed as a percentage of a flour weighing 25 g. Depending on the gluten content, several product categories are distinguished (Table 2.6).

The result of the analysis __________________________________________.

7. Determination of the quality of raw gluten. The quality of raw gluten is characterized by physical properties, extensibility and elasticity, color (light, gray, dark).

The extensibility of gluten is understood as its ability to stretch in length. To assess the quality of gluten by extensibility, 4 g of raw gluten is placed for 15 minutes in a glass of water at a temperature of 18 - 20 ° C. Further, taking a piece of gluten out of the water and squeezing it out, manually over the course of 10 s it is gradually stretched over the ruler into a tourniquet until it breaks, noticing how long the gluten has stretched. By extensibility, gluten is divided into: short - 10 cm, medium - extensibility 10 - 20 cm, long - extensibility more than 20 cm.

Under the elasticity of gluten is meant its ability to restore its original dimensions after its stretching. Under the elastic properties of gluten is meant the resistance to the action of compression load. To determine 4 g of gluten after soaking for 15 minutes in cold water at a temperature of 18 - 20 ° C is placed in the center on the instrument table of the pinetrometer. The working body of the pinetrometer is brought into contact with gluten, then it is loaded with 120 g. After 30 seconds, the load is removed and the amount of deformation is determined on the scale. When the deformation of the gluten is less than 37.5%, the quality of the gluten is very strong; at 37.5 - 55% - strong; 55 - 70% - average; 70 - 87.5% - satisfactorily weak, 87.5 - 100% - unsatisfactorily weak.

Record in the laboratory journal:

Weighing weight of raw gluten, g. . . . . . . . . . . . . . . . . . . . . . . . . . .___________

after the first washing, g. . . . . . . . . . . . . . . . . . . . .___________

after the second washing, g. . . . . . . . . . . . . . . . . . . . .___________

The amount of crude gluten,%. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .___________

Gluten color. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .___________

Extensibility. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .___________

Elasticity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .___________

The chemical composition of flour depends on the composition of the grain from which it is made, and on its variety. The higher the grade of flour, the more starch it contains. The content of other carbohydrates, as well as fat, ash, proteins and other substances, increases with a decrease in the grade of flour.
Features of the quantitative and qualitative composition of flour determine its nutritional value and baking properties.

Nitrogen and proteins

nitrogenous substances Flours are mostly made up of proteins. Non-protein nitrogenous substances (amino acids, amides, etc.) are contained in a small amount (2-3% of the total mass of nitrogenous compounds). The higher the yield of flour, the more nitrogenous substances and non-protein nitrogen are contained in it.
Wheat flour proteins. Simple proteins predominate in flour. Flour proteins have the following fractional composition (in%): prolamins 35.6; glutelins 28.2; globulins 12.6; albumins 5.2. The average content of proteins in wheat flour is 13-16%, insoluble protein is 8.7%.
Prolamins and glutelins of various cereals have their own characteristics in the amino acid composition, different physicochemical properties and different names.
Wheat and rye prolamins are called gliadins, barley prolamin is called hordein, maize prolamin is called zein, and wheat glutelin is called glutenin.
It should be borne in mind that albumins, globulins, prolamins and glutelins are not individual proteins, but only protein fractions isolated by various solvents.
The technological role of flour proteins in the preparation of bread products is very high. The structure of protein molecules and the physicochemical properties of proteins determine the rheological properties of the dough, affect the shape and quality of products. The nature of the secondary and tertiary structure of the protein molecule, as well as the technological properties of flour proteins, especially wheat, largely depend on the ratio of disulfide and sulfhydryl groups.
When kneading dough and other semi-finished products, proteins swell, adsorbing most of the moisture. Wheat and rye flour proteins are more hydrophilic, capable of absorbing up to 300% of water from their mass.
The optimum temperature for the swelling of gluten proteins is 30 °C. Gliadin and glutelin fractions of gluten, isolated separately, differ in structural and mechanical properties. The mass of hydrated glutelin is short extensible, elastic; the mass of gliadin is liquid, viscous, devoid of elasticity. The gluten formed by these proteins includes the structural and mechanical properties of both fractions. When baking bread, protein substances undergo thermal denaturation, forming a strong framework of bread.
The average content of raw gluten in wheat flour is 20-30%. In different batches of flour, the raw gluten content varies. wide range (16-35%).
The composition of gluten. Raw gluten contains 30-35% solids and 65-70% moisture. Gluten solids are 80-85% composed of proteins and various flour substances (lipids, carbohydrates, etc.), with which gliadin and glutenin react. Gluten proteins bind about half of the total amount of flour lipids. Gluten protein contains 19 amino acids. Glutamic acid predominates (about 39%), proline (14%) and leucine (8%). Gluten of different quality has the same amino acid composition, but different molecular structure. The rheological properties of gluten (elasticity, elasticity, extensibility) largely determine the baking value of wheat flour. There is a widespread theory about the significance of disulfide bonds in a protein molecule: the more disulfide bonds that occur in a protein molecule, the higher the elasticity and the lower the extensibility of gluten. There are fewer disulfide and hydrogen bonds in weak gluten than in strong gluten.
Rye flour proteins. According to the amino acid composition and properties, rye flour proteins differ from wheat flour proteins. Rye flour contains a lot of water-soluble proteins (about 36% of the total mass of protein substances) and salt-soluble (about 20%). The prolamin and glutelin fractions of rye flour are much lower in weight; they do not form gluten under normal conditions. The total protein content in rye flour is somewhat lower than in wheat flour (10-14%). Under special conditions, a protein mass can be isolated from rye flour, resembling gluten in elasticity and extensibility.
The hydrophilic properties of rye proteins are specific. They quickly swell when mixing flour with water, and a significant part of them swells indefinitely (peptizes), turning into a colloidal solution. The nutritional value of rye flour proteins is higher than that of wheat proteins, as they contain more essential amino acids in nutrition, especially lysine.

Carbohydrates
The carbohydrate complex of flour is dominated by higher polysaccharides (starch, fiber, hemicellulose, pentosans). A small amount of flour contains sugar-like polysaccharides (di- and trisaccharides) and simple sugars (glucose, fructose).
Starch. Starch, the most important carbohydrate in flour, is contained in the form of grains ranging in size from 0.002 to 0.15 mm. The size, shape, swellability and gelatinization of starch grains are different for different types of flour. The size and integrity of starch grains affects the consistency of the dough, its moisture capacity and sugar content. Small and damaged grains of starch are saccharified faster in the process of making bread than large and dense grains.
Starch grains, in addition to starch itself, contain a small amount of phosphoric, silicic and fatty acids, as well as other substances.
The structure of starch grains is crystalline, finely porous. Starch is characterized by a significant adsorption capacity, as a result of which it can bind a large amount of water even at a temperature of 30 ° C, i.e. at the dough temperature.
The starch grain is heterogeneous, it consists of two polysaccharides: amylose, which forms the inside of the starch grain, and amylopectin, which makes up its outer part. The quantitative ratios of amylose and amylopectin in the starch of various cereals are 1:3 or 1:3.5.
Amylose differs from amylopectin in its lower molecular weight and simpler molecular structure. The amylose molecule consists of 300-800 glucose residues forming straight chains. Amylopectin molecules have a branched structure and contain up to 6000 glucose residues. When starch is heated with water, amylose passes into a colloidal solution, and amylopectin swells, forming a paste. Full gelatinization of flour starch, in which its grains lose their shape, is carried out at a ratio of starch and water of 1: 10.
Subjected to gelatinization, starch grains increase significantly in volume, become loose and more pliable to the action of enzymes. The temperature at which the viscosity of the starch jelly is the highest is called the starch gelatinization temperature. The gelatinization temperature depends on the nature of the starch and on a number of external factors: the pH of the medium, the presence of electrolytes in the medium, etc.
The gelatinization temperature, viscosity and aging rate of starch paste in different types of starch are not the same. Rye starch gelatinizes at 50-55°C, wheat starch at 62-65°C, corn starch at 69-70°C. Such features of starch are of great importance for the quality of bread.
The presence of sodium chloride significantly increases the gelatinization temperature of starch.
The technological significance of flour starch in the production of bread is very high. The water absorption capacity of the dough, the processes of its fermentation, the structure of the bread crumb, taste, aroma, porosity of bread, and the rate of staleness of products largely depend on the state of starch grains. Starch grains bind a significant amount of moisture during dough kneading. The water absorption capacity of mechanically damaged and small grains of starch is especially high, since they have a large specific surface area. In the process of fermentation and proofing of the dough, part of the starch under the action of 3-amylase
saccharified, turning into maltose. The formation of maltose is necessary for the normal fermentation of the dough and the quality of the bread.
When baking bread, starch gelatinizes, binding up to 80% of the moisture in the dough, which ensures the formation of a dry, elastic bread crumb. During the storage of bread, starch paste undergoes aging (syneresis), which is the main reason for the staleness of bread products.

Cellulose. Cellulose (cellulose) is located in the peripheral parts of the grain and therefore is found in large quantities in flour of high yields. Wholemeal flour contains about 2.3% fiber, and wheat flour of the highest grade contains 0.1-0.15%. Fiber is not absorbed by the human body and reduces the nutritional value of flour. In some cases, a high fiber content is useful, as it accelerates the peristalsis of the intestinal tract.

Hemicelluloses. These are polysaccharides belonging to pentosans and hexosans. In terms of physicochemical properties, they occupy an intermediate position between starch and fiber. However, hemicelluloses are not absorbed by the human body. Wheat flour, depending on the variety, has a different content of pentosans - the main component of hemicellulose.
Flour of the highest grade contains 2.6% of the total amount of grain pentosans, and flour of the II grade contains 25.5%. Pentosans are divided into soluble and insoluble. Insoluble pentosans swell well in water, absorbing water in an amount exceeding their mass by 10 times.
Soluble pentosans or carbohydrate mucus give very viscous solutions, which, under the influence of oxidizing agents, turn into dense gels. Wheat flour contains 1.8-2% of mucus, rye flour - almost twice as much.

Lipids
Lipids are called fats and fat-like substances (lipoids). All lipids are insoluble in water and soluble in organic solvents.
The total lipid content in the whole grain of wheat is about 2.7%, and in wheat flour 1.6-2%. In flour, lipids are both in the free state and in the form of complexes with proteins (lipoproteins) and carbohydrates (glycolipids). Recent studies have shown that lipids associated with gluten proteins significantly affect its physical properties.

Fats. Fats are esters of glycerol and high molecular weight fatty acids. Wheat and rye flour of various varieties contains 1-2% fat. The fat found in flour has a liquid consistency. It consists mainly of glycerides of unsaturated fatty acids: oleic, linoleic (mainly) and linolenic. These acids have a high nutritional value, they are credited with vitamin properties. Hydrolysis of fat during storage of flour and further conversion of free fatty acids significantly affect the acidity, taste of flour and the properties of gluten.
Lipoids. Flour lipoids include phosphatides - esters of glycerol and fatty acids containing phosphoric acid combined with some nitrogenous base.

The flour contains 0.4-0.7% of phosphatides belonging to the group of lecithins, in which choline is the nitrogenous base. Lecithins and other phosphatides are characterized by high nutritional value and are of great biological importance. They easily form compounds with proteins (lipo-protein complexes), which play an important role in the life of every cell. Lecithins are hydrophilic colloids that swell well in water.
As surfactants, lecithins are also good food emulsifiers and bread improvers.

Pigments. Fat-soluble pigments include carotenoids and chlorophyll. The color of carotenoid pigments in flour is yellow or orange, and chlorophyll is green. Carotenoids have provitamin properties, as they are able to turn into vitamin A in the animal body.
The best known carotenoids are unsaturated hydrocarbons. When oxidized or reduced, carotenoid pigments turn into colorless substances. This property is the basis for the process of bleaching wheat flour, which is used in some foreign countries. In many countries, flour bleaching is prohibited, as it reduces its vitamin value. The fat-soluble vitamin of flour is vitamin E, the other vitamins of this group are practically absent in flour.

Minerals
Flour consists mainly of organic substances and a small amount of mineral (ash). The mineral substances of the grain are concentrated mainly in the aleurone layer, shells and embryo. Especially a lot of minerals in the aleurone layer. The content of minerals in the endosperm is low (0.3-0.5%) and increases from the center to the periphery, so the ash content is an indicator of the flour grade.
Most of the minerals in flour consist of phosphorus compounds (50%), as well as potassium (30%), magnesium and calcium (15%).
In negligible amounts contains various trace elements (copper, manganese, zinc, etc.). The iron content in the ashes of different types of flour is 0.18-0.26%. A significant proportion of phosphorus (50-70%) is presented in the form of phytin - (Ca - Mg - salt of inositol phosphoric acid). The higher the grade of flour, the less minerals it contains.

Enzymes
Cereal grains contain a variety of enzymes, concentrated mainly in the germ and peripheral parts of the grain. In view of this, high-yield flour contains more enzymes than low-yield flour.
Enzyme activity in different batches of flour of the same variety is different. It depends on the conditions of growth, storage, modes of drying and conditioning of the grain before grinding. Increased activity of enzymes was noted in flour obtained from unripe, sprouted, frost-bitten or bug-damaged grain. Drying grain under a hard regime reduces the activity of enzymes, while storing flour (or grain) it also decreases somewhat.
Enzymes are active only when the humidity of the environment is sufficient, therefore, when storing flour with a moisture content of 14.5% and below, the action of enzymes is very weak. After kneading, enzymatic reactions begin in semi-finished products, in which hydrolytic and redox flour enzymes participate. Hydrolytic enzymes (hydrolases) decompose complex flour substances into simpler water-soluble hydrolysis products.
It has been noted that proteolysis in wheat dough is activated by substances containing sulfhydryl groups and other substances with reducing properties (amino acid cysteine, sodium thiosulfate, etc.).
Substances with opposite properties (with the properties of oxidizing agents) significantly inhibit proteolysis, strengthen gluten and the consistency of wheat dough. These include calcium peroxide, potassium bromate and many other oxidizers. The effect of oxidizing and reducing agents on the process of proteolysis is already felt at very low dosages of these substances (hundredths and thousandths of a % of the mass of flour). There is a theory that the effect of oxidizing and reducing agents on proteolysis is explained by the fact that they change the ratio of sulfhydryl groups and disulfide bonds in the protein molecule, and possibly the enzyme itself. Under the action of oxidizing agents, disulfide bonds are formed due to the groups, which strengthen the structure of the protein molecule. Reducing agents break these bonds, which causes the gluten and wheat dough to weaken. The chemistry of the action of oxidizing and reducing agents on proteolysis has not been finally established.
The autolytic activity of wheat and especially rye flour is the most important indicator of its baking value. Autolytic processes in semi-finished products during their fermentation, proofing and baking should proceed with a certain intensity. With increased or decreased auto-lytic activity of flour, the rheological properties of the dough and the nature of the fermentation of semi-finished products change for the worse, and various bread defects occur. In order to regulate autolytic processes, it is necessary to know the properties of the most important flour enzymes. The main hydrolytic flour enzymes are proteolytic and amylolytic enzymes.

Proteolytic Enzymes. They act on proteins and their hydrolysis products.
The most important group of proteolytic enzymes are proteinases. Papain-type proteinases are found in grains and flours of various cereals. The optimal indicators for the action of grain proteinases are pH 4-5.5 and temperature 45-47 ° C -
During dough fermentation, grain proteinases cause partial proteolysis of proteins.
The intensity of proteolysis depends on the activity of proteinases and on the susceptibility of proteins to the action of enzymes.
Proteinases of flour obtained from grain of normal quality are not very active. Increased activity of proteinases is observed in flour made from sprouted grains and especially from grains affected by the tortoise bug. The saliva of this pest contains strong proteolytic enzymes that penetrate the grain when bitten. During fermentation, in a dough made from flour of normal quality, the initial stage of proteolysis occurs without a noticeable accumulation of water-soluble nitrogen.
During the preparation of wheat bread, proteolytic processes are regulated by changing the temperature and acidity of semi-finished products and adding oxidizing agents. Proteolysis is somewhat inhibited by table salt.

Amylolytic enzymes. These are p- and a-amylases. p-Amylase was found both in germinated grains of cereals and in grains of normal quality; a-amylase is found only in sprouted grains. However, a noticeable amount of active a-amylase was found in rye grain (flour) of normal quality. a-Amylase refers to metalloproteins; its molecule contains calcium, p- and a-amylases are found in flour mainly in a state associated with protein substances and are split after proteolysis. Both amylases hydrolyze starch and dextrins. The most easily decomposed by amylases are mechanically damaged grains of starch, as well as gluten starch. The works of I. V. Glazunov established that 335 times more maltose is formed during the saccharification of dextrins with p-amylase than during the saccharification of starch. Native starch is hydrolyzed by p-amylase very slowly. p-Amylase, acting on amylose, converts it completely into maltose. When exposed to amylopectin, p-amylase cleaves maltose only from the free ends of the glucoside chains, causing hydrolysis of 50-54% of the amount of amylopectin. The high molecular weight dextrins formed in this process retain the hydrophilic properties of starch. a-amylase cleaves off branches of the glucosidic chains of amylopectin, turning it into low molecular weight dextrins that are not stained with iodine and lack the hydrophilic properties of starch. Therefore, under the action of a-amylase, the substrate is significantly liquefied. Then dextrins are hydrolyzed by a-amylase to maltose. The thermolability and sensitivity to the pH of the medium are different for both amylases: a-amylase is more thermally stable than (3-amylase), but more sensitive to acidification of the substrate (lowering the pH). 6 and a temperature of 45-50 ° C. At a temperature of 70 ° C, p-amylase is inactivated. The optimum temperature of a-amylase is 58-60 ° C, pH 5.4-5.8. The effect of temperature on the activity of a-amylase depends on reaction of the medium As the pH decreases, both the temperature optimum and the temperature of α-amylase inactivation decrease.
According to some researchers, flour a-amylase is inactivated during bread baking at a temperature of 80-85 °C, however, some studies show that a-amylase is inactivated in wheat bread only at a temperature of 97-98 °C.
The activity of a-amylase is significantly reduced in the presence of 2% sodium chloride or 2% calcium chloride (in an acidic environment).
p-Amylase loses its activity when exposed to substances (oxidizing agents) that convert sulfhydryl groups into disulfide ones. Cysteine ​​and other drugs with proteolytic activity activate p-amylase. Weak heating of the water-flour suspension (40-50 ° C) for 30-60 minutes increases the activity of flour p-amylase by 30-40%. Heating to a temperature of 60-70 °C reduces the activity of this enzyme.
The technological significance of both amylases is different.
During dough fermentation, p-amylase saccharifies some of the starch (mainly mechanically damaged grains) to form maltose. Maltose is necessary to obtain loose dough and normal quality of products from varietal wheat flour (if sugar is not included in the product recipe).
The saccharifying effect of p-amylase on starch increases significantly during starch gelatinization, as well as in the presence of a-amylase.
Dextrins formed by a-amylase are saccharified by p-amylase much more easily than starch.
Under the action of both amylases, starch can be completely hydrolyzed, while p-amylase alone hydrolyzes it by about 64%.
The optimum temperature for a-amylase is created in the dough when baking bread from it. Increased activity of a-amylase can lead to the formation of a significant amount of dextrins in the bread crumb. Low molecular weight dextrins bind the moisture of the crumb poorly, so it becomes sticky and wrinkled. The activity of a-amylase in wheat and rye flour is usually judged by the autolytic activity of the flour, determining it by the falling number or by the autolytic test. In addition to amylolytic and proteolytic enzymes, other enzymes influence the properties of flour and the quality of bread: lipase, lipoxygenase, polyphenol oxidase.

Lipase. Lipase breaks down flour fats during storage into glycerol and free fatty acids. In wheat grain, lipase activity is low. The greater the yield of flour, the higher the comparative activity of lipase. The optimum action of grain lipase is at pH 8.0. Free fatty acids are the main acid reacting substances in flour. They can undergo further transformations that affect the quality of flour - dough - bread.
Lipoxygenase. Lipoxygenase is one of the redox enzymes in flour. It catalyzes the oxidation of certain unsaturated fatty acids by atmospheric oxygen, converting them into hydroperoxides. The most intensively lipoxygenase oxidizes linoleic, arachidonic and linolenic acids, which are part of the grain fat (flour). In the same way, but more slowly, lipoxygenase in the composition of native fats acts on fatty acids.
The optimal parameters for the action of lipoxygenase are a temperature of 30-40 °C and a pH of 5-5.5.
Hydroperoxides formed from fatty acids under the action of lipoxygenase are themselves strong oxidizing agents and have a corresponding effect on the properties of gluten.
Lipoxygenase is found in many cereals, including rye and wheat grains.
Polyphenol oxidase (tyrosinase) catalyzes the oxidation of the amino acid tyrosine with the formation of dark-colored substances - melanins, which cause darkening of the bread crumb from high-quality flour. Polyphenol oxidase is found mainly in high yield flours. In grade II wheat flour, a greater activity of this enzyme is observed than in premium or grade I flour. The ability of flour to darken during processing depends not only on the activity of polyphenol oxidase, but also on the content of free tyrosine, the amount of which is insignificant in flour of normal quality. Tyrosine is formed during the hydrolysis of protein substances, therefore flour from sprouted grain or affected by a bug-turtle, where proteolysis is intensive, has a high ability to darken (almost twice as high as that of normal flour). The acid optimum of polyphenol oxidase is in the pH zone of 7-7.5, and the temperature optimum is at 40-50 °C. At a pH below 5.5, polyphenol oxidase is inactive, therefore, when processing flour that has the ability to brown, it is recommended to increase the acidity of the dough within the required limits.

CLASSIFICATION

Flour is a powdery product obtained by grinding grain with or without separating the bran,

Depending on the raw materials (grain) used, flour is divided into types: the main ones are wheat and rye; secondary - barley, corn and soy (can be used in baking, but in small quantities); special purpose - oatmeal, rice, buckwheat, pea (used in food of the concentrate industry); swelling flour (for the production of custard varieties of bread).

Depending on the intended use, wheat flour is divided into baking, pasta and general purpose. Wheat flour produced from soft wheat or with the addition of 20% durum wheat (durum) is intended for the production of bread, bakery products, flour confectionery and culinary products, as well as retail sales. Wheat flour, produced from durum wheat (durum), is intended for the production of pasta.

Rye flour is produced only for baking. Soybean flour is divided according to its fat content: full-fat, semi-skimmed and defatted.

By quality, flour is divided into commercial grades. The type of flour will depend on what part of the grain gets into the flour, i.e., "on the technology of grain processing. Wheat baking flour is produced from six grades: extra, higher, coarse, first, second and wholemeal. Rye baking flour ~ three grades: sown, peeled and wholemeal barley - two varieties: single-grade and wholemeal corn - three varieties: fine grinding, coarse grinding and wholemeal Deodorized soybean flour, regardless of the fat content, is divided into two grades: the highest and the first.

Wheat flour of general purpose is divided into types depending on the fineness, whiteness or mass fraction of ash, mass fraction of raw gluten: M 45-23; M 55-23; M 75-23; M 100-25; M 125-20;

M 145-23; MK 55-23: MK 75-23.

FLOUR ASSORTMENT

Wheat flour

Types of flour. Wheat flour is produced for baking, general purpose and pasta. ..,:"

Wheat baking flour produced six varieties: extra, grain, higher, first, second and wallpaper.

Flour of different varieties has a different degree of grinding and chemical composition. With a decrease in the grade of flour, the amount of vitamins, mineral elements increases, and in the proteins of albumins and globulins containing essential amino acids. But products of lower grades are darker in color, are less digestible and have worse baking qualities. Flour of the highest grade has the highest calorie content.

Flour extra - consists of finely divided particles of the central part of the endosperm, does not contain bran, is white or white with a creamy tint. Ash content - not more than 0.45%, the amount of "crude gluten" - not less than 28%, the falling number - not less than 185 s.

Premium flour consists of finely divided particles (average particle size of 140 microns or less) of the central part of the endosperm, contains practically no bran, is white or white with a creamy tint. Ash content - no more than 0 55%, the amount of raw gluten - no less than 28%, the falling number - no less than 185s.

grain It is produced from vitreous soft wheat with the addition of durum. Represents large particles (200 ... 300 microns consists of pure endosperm of the central parts of the grain. It is distinguished by the uniformity of particles of a grainy structure, a large co-1 | M. we are looking for protein. It has a white color with a yellowish tinge. Gluten content is at least 30% good quality, ash content - not less than 185, falling number - not less than 185s.

Flour of the first grade - the most common type of flour for the production of bakery products. Flour of this variety is finely ground particles (up to 160 microns) of all layers of endosper MA, contains 3...4% bran, white with a yellowish tinge. Ash content - no more than 0.75%, the amount of raw gluten - no less . it is 30%, the falling number is not less than 185s.

Flour of the second grade consists of heterogeneous particles of crushed endosperm (from 30 to 20 microns), with an admixture of crushed shells (bran) up to 10%. As a result of the presence of shell particles, the flour acquires a grayish tint. The ash content is increased to 1.25%, while the gluten content and the falling number are reduced to 25% and 160 s, respectively.

Whole flour obtained by grinding the whole grain and contains up to 16% bran. Flour is not uniform in size. Color - white with yellowish or grayish hues with noticeable particles of grain shells. The content of crude gluten is not less than 20%, the falling number is not less than 160s, and the ash content should not exceed 2%.

All purpose wheat flour depending on the whiteness or mass fraction of ash, mass fraction of raw gluten is divided into types: M 45-23; M 55-23; M 75-23; M 100-25; M 125-20; M 145-23 and also on the grinding size: MK 55-23; MK 75-23. Letter "M" convoy starts flour from soft wheat, the letters "MK" - flour from soft wheat of coarse grinding. The first digits indicate the largest mass fraction of ash in flour in terms of dry matter as a percentage multiplied by 100, and the second - the smallest mass fraction of crude "gluten in flour as a percentage. General purpose flour differs from baking more low gluten content (20...23%),

Flour for the confectionery industry produced at a reduced content squirrel(8...10%) and included in the group of wheat flour of general purpose. The protein content is regulated by redistribution between flour varieties during grinding. Smaller factions flour is the richest proteins and have a lower density than fractions containing more starch. The obtained high-protein fractions are used to enrich baking flour or for other purposes, and low-protein fractions are used to obtain flour, which is used in the confectionery industry.

Pasta wheat flour three grades are produced: the highest grade (krupka), the first grade (semi-grain) and the second grade. The flour of the highest (grains) and the 1st (semi-grains) varieties of durum wheat obtained as a result of these grindings must comply with the requirements of GOST 12307 "Durum wheat flour (durum) for pasta", flour of the 2nd grade - the requirements of GOST 16439 "Flour of the second varieties from durum wheat "Durum", and flour of the highest (grain) and 1 grade (semi-grain) soft vitreous wheat - the requirements of GOST 12306 "Flour from soft vitreous wheat for pasta".

Pasta flour differs from bread flour in that it contains a lot of protein and has a grainy structure. Due to the granular structure, despite the high protein content, the flour has a reduced water absorption capacity. The glucoin contained in it should be good and belong to the first or second groups. Flour with gluten of the third group is unsuitable for the production of pasta, since raw products are fragile. .

There are pasta flours made from durum and high vitreous soft wheat. Such a division is also accepted in world practice (“se-molina” - from durum and “farina” - from soft wheat).

The best flour for the production of pasta is durum wheat flour. It differs in cream color of various shades depending on the variety, granular structure and glassy consistency of the particles that form it. Flour of the highest grade (semolina) consists of the inner layers of the endosperm and has a creamy color with a yellow tint, and flour of the 1st grade is predominantly from particles of the peripheral endosperm with a more or less noticeable amount of shell particles that are relatively unnoticeable in flour due to the weak pigmentation of durum wheat shells ; the color of flour I grade is light cream. Flour of the second grade is also characterized by a cream color with a yellowish tinge.

Pasta flour made from soft high vitreous wheat is pure white with yellow or creamy tints, depending on the variety. It contains less protein and more starch than durum wheat pasta. Products from it are white, less vitreous, but in appearance differ little from products made from durum wheat; and consumer properties of finished pasta are much worse

Enriched flour. Wheat flour can be enriched with vitamins and/or minerals in accordance with the standards approved by the Russian Ministry of Health, as well as baking improvers, including dry gluten. To the name of such flour, respectively, add: "fortified", "enriched with minerals", "enriched with a vitamin-mineral mixture", "enriched with dry gluten" or other baking improvers. In terms of quality, fortified flour must meet the requirements of the corresponding grade according to GOST R 52189-2003.

Fortification of wheat flour is carried out due to the fact that high-grade flour does not contain the required amount of vitamins, therefore, at the final stage of production, it can be fortified with vitamins B, B, PP. Synthetic vitamins are introduced into flour of the highest and first grades (in mg / 100 g):

b| - 0.4; Vz - 0.4; PP - 2.0. Vitamins are administered in a complex, but only vitamin PP can be added. In flour enriched with vitamins, a slight odor characteristic of vitamin B | (thiamine).

In developed countries, wheat flour is usually fortified not only with vitamins b], Vd. niacin, but also iron. In some countries calcium is added. Vitamins A and O can be added to flour. This experience is of interest to Russia. Levels added to wheat. flour of vitamins B], niacin and iron are often equal to the amount lost during grinding, and vitamin B ^ - the amount added exceeds the amount lost during grinding. Most developed Western countries, as well as in many developing countries in Africa, Asia and Latin America, fortify food with vitamins and minerals by law. The amount of vitamins is regulated by state laws, indicated on individual packaging and strictly controlled by state oversight bodies. So, for example, in the USA since 1974, and in Canada since, 1978. mandatory fortification of all flour, regardless of variety, is carried out with a whole complex of micronutrients - vitamins b |, B ^, B, PP, A, folic acid, iron, calcium, magnesium and zinc in such quantities that 450 g of flour provides the recommended consumption rate these substances.

Rye flour is produced only by baking flour of three varieties: seeded, peeled and wholemeal.

Seeded flour - finely ground particles of grain endosperm with the number of shells 1 ... 3%. It is white in color with creamy or grayish hues. Ash content - no more than 0.75 %, falling number - 160s. It is obtained mainly from the endosperm. Therefore, it is characterized by the highest content of starch and a relatively low content of proteins, sugars, non-starch polysaccharides, fat and minerals.

Peeled flour heterogeneous in size with the content of shell particles up to 15%, which are visible to the naked eye when assessing the color. The color is grayish-white or grayish-cream. Ash content - 1.45%, falling number - 150 s.

Whole flour - particles inhomogeneous in size, obtained by grinding all parts of the grain. Color - gray with particles of grain shells, ash content not more than 2%, falling number - 105 s.

Baking rye flour "Special" according to TU 11-115-92 is produced. It occupies an intermediate position between seeded rye flour and peeled flour, produced according to GOST, in terms of ash content (1.15%).

Rye flour does not form gluten, but contains more water- and salt-soluble proteins that are complete in amino acid composition. "

The gas-forming ability of rye flour is always quite high. Often the activity of the amylase enzyme is so high that a large amount of dextrins accumulate in the bread during baking due to the hydrolysis of starch under its influence, as a result of which the bread crumb becomes sticky to the touch, wrinkling, and inelastic. Therefore, the quality of rye flour is usually determined by its autolytic activity. If the autolytic activity of rye flour is high, its quality is low. The autolytic activity of rye flour (wallpaper) in terms of the amount of water-soluble substances (in % on dry basis) is estimated as follows: reduced - up to 40; normal - 41 ... 55; increased - 56 ... 65; sharply increased - over 65. For peeled rye and o-wheat flour, it should be no more than 50%.The high autolytic activity of the flour can lead to bread with a sticky crumb crumb.

The water absorption capacity of rye flour is greater than that of wheat flour. This is due to the content of mucus in rye flour, which swells well, absorbing a large amount of water.

soy flour

Soy flour is produced deodorized full fat, semi-skimmed, fat-free. Different types of soy flour differ in the method of preparation and chemical composition, mainly in the content of protein (crude protein) and fat. The most important component of soy flour are proteins, which are contained (in g per 100g of the product);

36.5 in full-fat, 43.0 in semi-skimmed, and 49.0 in skim. In terms of amino acid composition, soy proteins are close to meat proteins, and in digestibility - to milk casein. The amount of water-soluble proteins reaches 87...90%. Compared to the squirrels of evil-. coves and peas, soy proteins contain more essential amino acids - lysine, leucine, valine, threonine, tryptophan, but relatively little methionine. The starch content ranges from 10 to 15 g per 10 g. depending on the type of flour.

Whole fat soy flour obtained from light-colored soybean seeds, which are pre-cleaned, deodorized (steamed and dried) to eliminate the specific “bean” odor caused by lipid oxidation, the shells are separated and ground into a fine flour. Deodorized full fat soy flour contains at least 17% fat and 38% crude protein.

Semi-skimmed soy flour obtained from oil cake, which is a by-product of the extraction of soybean oil by pressing. The flour contains 5.-.8% fat and at least 43% crude protein. Semi-fat deodorized soy flour can be presented in the form of a soy protein product "Soyushka" (TU 92293-013-10126558-98) with a fat mass fraction of not more than 14%. Defatted soy flour obtained from meal - the product remaining after the extraction of fat by the extraction method. Flour contains no more than 2% fat and 48% crude protein.

In terms of quality, soy flour of all types is divided into two grades - the highest and the first, depending on the fiber content: 3.5 and 4.5% in non-fat, 4.5 and 5.0% - in semi-skimmed and skimmed, respectively for flour of the highest and the first grades (tab. 25).

Issued reconstituted soy flourfat behind by adding refined oil in an amount of 1 to 15%, which reduces dust formation and brings the fat content to the required amount. Lecithinated soy flour issued with the addition

Leniy 3; 6 and 15% lecithin and is used in the production of flour confectionery. Lecithin improves flour dispersibility and | other ingredients in the composition of confectionery products.

soy flour is used for different purposes: in baking to increase the nutritional value of bakery products.

Chemical composition of flour primarily due to the composition of the grain from which it is obtained. Almost all substances that are present in the grain pass into flour, their quantity and ratio depend on the type of flour. The higher the grade of flour, the more particles of pure endosperm in it and the less bran. Different types of flour differ in chemical composition.

With an increase in the grade of flour, the content of carbohydrates, mainly starch, increases. The amount of other nutrients - proteins and fats, as well as mineral salts and fiber is reduced. This is due to the fact that the highest grade flour is produced from almost pure endosperm, rich in starch, while lower grade flour contains a certain amount of bran, rich in fiber, mineral salts, fats and proteins. The lower the grade of flour, the closer its chemical composition to the composition of the grain. In terms of chemical composition, wholemeal flour almost does not differ from grain, since it is a grain that has been ground with little or no separation of the bran. Thus, low-grade flour contains a variety of useful substances, but its digestibility is somewhat reduced due to the significant fiber content; for example, in wholemeal flour, fiber is about 2%, and in premium flour - 0.1%. Flour of the highest grades is poorer in useful substances, especially mineral salts and vitamins, but it is absorbed much more fully and easily.

The chemical composition of flour determines its nutritional value and baking properties. The most important substances in flour are proteins and carbohydrates. The baking qualities and quality of bread depend on the amount of proteins and their properties.

Proteins, depending on the type and variety, the flour contains from 9 to 16%. In the flour of the highest grades, they are less. This is due to the fact that proteins are unevenly distributed in the endosperm: there are more of them in the outer layer and less in the central part, from which the highest grades of flour are obtained. Flour of lower grades is richer in proteins also because it contains an aleurone layer and a germ co significant reserves of proteins.

Rye flour proteins differ in composition and properties from wheat flour proteins. About half of the rye flour proteins are soluble in water and do not form gluten, but they are higher in nutritional value than wheat flour proteins, as they are richer in essential amino acids.

The carbohydrates in flour are mainly starch and fiber. There is an inverse relationship between them: with an increase in the grade of flour, the starch content increases, but the amount of fiber decreases. On average, flour contains about 75% starch. There are relatively few sugars in flour.

Fat in flour contains no more than 2%, they are easily oxidized and quickly rancid during storage. The lower grades of flour are richer in fats, since they contain more particles of the aleurone layer and germ, in which fats are mainly concentrated. In flour lipids, unsaturated fatty acids occupy 74–81%, linoleic acid predominates (52–65%), and there are less of these acids in bound lipids. The fatty acid composition is of great importance for characterizing the baking qualities of flour, as well as its changes during storage.

The mineral substances of flour are represented by: phosphorus, calcium, iron, potassium, magnesium, sodium, manganese, copper, zinc, etc. These substances are mainly found in the shells, the aleurone layer and the germ, therefore low-grade flour is richer in mineral compounds compared to higher ones.

The mineral substances of flour are represented by salts of phosphoric acid, and are also part of organic compounds - proteins, starch, phytin, phospholipids.

Of the vitamins in flour, there are B1 (0.17-0.41), B2 (0.04-0.15), B6 ​​(0.17-0.55), PP (1.2-5.5 mg%) and E (2.57-5.50 mg%), as well as carotene in wallpaper flour 0.01, in flour of the 2nd grade 0.005 mg%). The highest grades of flour are poor in vitamins, since the aleurone layer and the germ in which they are concentrated are removed during varietal grinding.

Flour enzymes play an important role in kneading and fermenting dough. Of the numerous enzymes, the most important are amylases, which catalyze the breakdown of starch, and proteases, which catalyze the breakdown of proteins.

25. Cereals. Assortment, nutritional value, quality expertise

26 Corn oil. The nutritional value. Requirements for quality, packaging, storage

The tables show the organoleptic and physico-chemical parameters of corn oil (GOST 8808-2000).

Table - Organoleptic characteristics of corn oil

Name of indicator
	refined		Unrefined brand P
	deodorized brands D and P	non-deodorized brand SK
Transparency	Transparent without sediment		Slight turbidity is allowed above the sediment
Smell and taste	Odorless, taste of impersonal oil	Peculiar to refined corn oil, without foreign smell, aftertaste and bitterness	Peculiar to corn oil, no foreign smell

Refined corn oil should be clear with no sediment. AT unrefined, slight turbidity over the sediment is allowed. Refined deodorized oil must be depersonalized in taste and smell. Refined, non-deodorized and unrefined oils have a taste and smell characteristic of corn oil, without foreign smell and taste, there should be no bitterness.

Table - Physical and chemical indicators of corn oil

Name of indicator	Characteristics of corn oil
	refined			nerafini- roved
	deodori- roved		non-deodoro- roved
Color number, mg iodine, no more
Acid number, mg KOH/g, no more
Mass fraction of non-fatty impurities, %, no more	absence
Mass fraction of phosphorus-containing substances in terms of stearo-oleolecithin,%, no more
Soap (quality test)	absence			not standardized
Flash point of extraction oil, 0 C, not lower
peroxide number, mmol 1/2 O/kg, no more

The shelf life of corn oil (from the date of production) is set by the manufacturer depending on the production scheme, storage temperature, availability of consumer packaging and type of packaging material.

Flour obtained after grinding wheat grains. It is the most common type of flour.

Kinds

In Russia, flour is classified according to the degree of processing into flour of the highest, first and second grade, wholemeal and whole grain.

Wheat flour of the highest grade, or “extra”, is distinguished by its snow-white color, sometimes with a creamy tint, and the smallest grains that are not felt when rubbed with fingers. It is used in the preparation of rich products, airy muffins, biscuits, cakes, thickening sauces. This flour contains few substances useful for the body, therefore it is not recommended for daily use.

Flour of the first grade contains a small amount of grain shells and a lot of gluten, which provides the dough prepared from it with elasticity, shape maintenance, volume and longer shelf life of finished products. It is suitable for making pancakes, pies, shortbread, puff pastry, yeast dough, flour dressings and sauces.

Flour of the second grade contains up to 8% bran and is characterized by a darkish color. It is used for table white bread and lean flour products.

Whole flour, or wholemeal flour, is made by grinding wheat grains to heterogeneous and large grains. In this case, the germ and shell of the grain are sifted out.

Whole grain flour is the result of grinding wheat grain without preliminary purification from the shell and germs. The most useful type of bread is prepared from it, as well as other products that contain a large amount of vitamins, minerals and fiber.

calories

100 grams of the product contains 328 kcal.

Compound

Wheat flour contains carbohydrates, dietary fiber, starch, proteins, fats, saccharides, ash, vitamins B1, B2, B3, B6, B9, H, E, PP, as well as mineral elements: potassium, magnesium, zinc, manganese, calcium, iron, sodium, silicon, phosphorus, chlorine, sulfur, molybdenum, iodine, copper, fluorine, aluminum, cobalt, nickel.

The amount of nutrients in flour varies depending on the variety.

Usage

Wheat flour is used for the manufacture of bakery products, cakes, cookies, pancakes, fritters, dumplings, dumplings, pasta, sauces, breading, etc.

Beneficial features

Products made from wheat flour fill the body with energy, activate mental activity, and have a beneficial effect on the state of the blood and nervous system.

Use restrictions

A large amount of flour products can lead to weight gain.

People suffering from certain diseases of the gastrointestinal tract should give preference to premium flour.

Introduction

flour classification

The nutritional value

1.1 Chemical composition of flour

1.2 Nutritional and energy value

Factors that shape the quality of flour

1.3 Raw material

1.4Technology of flour production

1.5Technological defects and defects

Factors Preserving Flour Quality

1.6Packaging and labeling of flour

1.7Storage and transport

1.8 Implementation

1.9Falsification of flour

Flour quality assessment

1.10Organoleptic indicators

1.11 Physical and chemical parameters

1.12Safety performance

Conclusion

Bibliography

Appendix

Introduction

In this term paper on the topic: "Commodity characteristics of flour" we will consider such key issues as:

- Nutritional value, chemical composition of wheat and rye flour

- Classification and range

- Quality, defects of wheat and rye flour

- Packaging, labeling, storage of wheat and rye flour.

The relevance of the topic of the course work is due to the fact that today a lot of attention is paid by consumers to the quality of products. The successful promotion of the product on the consumer market and its ability to compete with similar products depend on the quality. Flour is a powdered product obtained by grinding cereal grains.

The flour milling industry is the largest branch of the food industry, which produces flour for retail trade, as well as for baking, confectionery and other industries. Flour is the main product of grain processing, it is of paramount importance in supplying the population with essential products, as it is used to make baked bread.

The group of grain products occupies almost 20% of the consumer basket of a Russian. Groats, bakery products, pasta are essential goods, so the flour and cereals market can be called socially significant.

Wheat flour- flour obtained from wheat grains.

Wheat flour is perhaps the most popular baking flour in the world. It comes in several types.

Premium flour (the word “extra” is written on some packages) has quite a bit of gluten, and it looks completely white. Such flour is ideal for pastries, it is often used as a thickener in sauces.

Flour of the first grade is good for lean pastries, and its products become stale much more slowly. In France, it is customary to bake bread from wheat flour of the first grade.

As for second grade flour, it contains up to 8% bran, so it is much darker than first grade. It is used in our country - it is from it that lean products and ordinary white bread are made, and mixed with rye flour - black.

Rye is one of the most important cereal crops. The consumption rate of rye flour (as a percentage of all cereals) is about 30.

Rye flour has numerous beneficial properties. It contains the amino acid necessary for our body - lysine, fiber, manganese, zinc. Rye flour contains 30% more iron than wheat flour, as well as 1.5-2 times more magnesium and potassium. Rye bread is baked without yeast and on thick sourdough.

Therefore, the use of rye bread helps to reduce cholesterol in the blood, improves metabolism, heart function, removes toxins, helps prevent dozens of diseases, including cancer.

Due to the high acidity (7-12 degrees), which protects against the occurrence of mold and destructive processes, rye bread is not recommended for people with high acidity of the intestines, suffering from peptic ulcers. The 100% rye bread is really too heavy for daily consumption. The best option: rye 80-85% and wheat 15-25%. Varieties of rye bread: from white flour, from peeled flour, rich, simple, custard, Moscow, etc.

The purpose of this course work is to consider the main characteristics of wheat and rye flour, as well as to identify the requirements for the quality of flour sold on the territory of the Russian Federation and the GOSTs regulating it.

To achieve this goal, it is necessary to perform a number of tasks:

- to study the nutritional value, chemical composition of wheat and rye flour

- to consider the classification and assortment

- disclose such indicators as: quality, defects of wheat and rye flour

- consider the rules for packaging, labeling and storage of wheat and rye flour

- Analyze the range of new products.

flour classification

In accordance with GOST R 52189-2003 Flour wheat . General specifications. Wheat flour, depending on its intended use, is divided into:

wheat bakery;

general purpose wheat.

Wheat bread flour depending on the whiteness or mass fraction of ash, mass fraction of crude gluten, as well as the fineness of grinding, they are divided into varieties: extra, higher, grit, first, second and wallpaper.

All-purpose wheat flour depending on the whiteness or mass fraction of ash, the mass fraction of raw gluten, as well as the fineness of grinding, they are divided into types: M45-23; M 55-23; MK 55-23; M 75-23; MK 75-23; M 100-25; M 125-20; M 145-23.

Wheat flour can be enriched with vitamins and/or minerals in accordance with the standards approved by the Russian Ministry of Health, as well as baking improvers, including dry gluten, in accordance with the approved regulatory document.

To the name of such flour, respectively, add: "fortified", "enriched with minerals", "enriched with a vitamin-mineral mixture", "enriched with dry gluten" and other baking improvers.

In flour enriched with vitamins, a slight odor characteristic of vitamin B1 (thiamine) is allowed.

Baking wheat flour is produced for retail, confectionery and baking industries. By quality, it is divided into grains, flour of the highest, 1st and 2nd grade, as well as wallpaper. Varieties of flour differ in color, grinding size, chemical composition, gluten content, baking properties and other indicators.

Krupchatka obtained from glassy soft and hard wheats. Flour in the form of homogeneous grains of yellow-cream color; flour yield - 10%; its ash content is 0.6%; crude gluten content – ​​30%. Used for baking sweets and pasta.

Flour of the highest grade are made from soft glassy and semi-glassy wheats. The flour is soft to the touch, the color is white or white with a creamy tint; flour yield - 10-15; 40%; ash content - 0.55%; raw gluten content 28%. Used for sale to the population, production of confectionery and bakery products.

Flour of the 1st grade obtained from soft and vitreous wheats. It is soft, white in color with a slight yellowish tint; yield - from 30 to 72% (depending on the method of grinding); ash content - 0.75%; crude gluten content - 30%. This flour is widely used in the baking, confectionery industry, as well as for sale to the population.

2nd grade flour made from soft wheat. Its particles are heterogeneous in size; color white with a yellowish-grayish tint; flour yield - up to 85%; ash content - 1.25%; gluten content not less than 25%. It is used to make bread.

wallpaper flour obtained from soft wheats with single-grade wholemeal grinding without screening out bran, so the flour yield is high - 96%; flour particles are heterogeneous in size; grayish white color; ash content - up to 2%; gluten content - 20%. Flour is used to make bread.

Wheat flour for pasta. It is obtained by special three-grade grinding of durum wheat with a high content of good quality gluten. The particles of this flour are larger than bread flour. According to the quality, pasta flour is divided into the highest (grains) and the 1st (semi-grains) grades. Cream-colored premium flour; ash content of flour - 0.7%; raw gluten - 28-30%. Flour of the 1st grade is softer; ash content of flour - 1.1%, gluten - 30-32%.

In accordance with GOST R 52809-2007 baking rye flour, depending on the quality, is divided into varieties:

• peeling;

Seeded flour- the highest quality grade of rye flour. It consists of finely ground rye grain endosperm with a small admixture of particles of the aleurone layer and shells (only about 4% of the flour mass). Particle size from 20 to 200 microns. The color of the flour is white with a bluish tinge. Flour is rich in starch (71-73%), sugars (4.7-5.0%), contains a significant amount of water-soluble substances and relatively little protein (8-10%) and fiber (0.3-0.4%). The ash content of flour is 0.65-0.75%.

Peeled flour differs from the wallpaper in a lower content of shells and an aleurone layer of grain (12-15% of the mass of flour), as well as a higher degree of grinding. Particle size from 30 to 400 microns. The color of the flour is white with a gray or brownish tint. Peeled flour, like wholemeal flour, is rich in water-soluble substances, but contains less protein (10-12%), more starch (66-68%). The fiber content in this flour is 0.9-1.1%, and the ash content of the flour is 1.2-1.4%.

Whole flour is a grain of rye, ground after cleaning it from impurities and processing on scouring machines. Flour is obtained with single-grade 95% grinding by passing through wire sieves 067.

Wholemeal flour consists of the same tissues as rye grain (with a slightly smaller amount of fruit shells and germ) and contains, along with crushed endosperm, 20-25% of crushed shells and the aleurone layer. Particle size from 30 to 600 microns. The color of the flour is white with a pronounced gray, yellowish or greenish tint, depending on the color of the rye grain. Flour is rich in water-soluble substances, sugar contains 12-14% protein, 60-64% starch, fiber - 2-2.5%, ash content - 1.8-1.9%.

The nutritional value

The chemical composition of flour.

The chemical composition of flour depends on the composition of the grain from which it is made, and on its variety. The higher the grade of flour, the more starch it contains. The content of other carbohydrates, as well as fat, ash, proteins and other substances, increases with a decrease in the grade of flour.

Consider the features of the quantitative and qualitative composition of flour determine its nutritional value and baking properties.

Nitrogen and proteins

The nitrogenous substances of flour are mainly composed of proteins. Non-protein nitrogenous substances (amino acids, amides, etc.) are contained in a small amount (2-3% of the total mass of nitrogenous compounds). The higher the yield of flour, the more nitrogenous substances and non-protein nitrogen are contained in it.

Wheat flour proteins. Simple proteins predominate in flour. Flour proteins have the following fractional composition (in%): prolamins 35.6; glutelins 28.2; globulins 12.6; albumins 5.2. The average content of proteins in wheat flour is 13-16%, insoluble protein is 8.7%.

The composition of gluten. Raw gluten contains 30-35% solids and 65-70% moisture. Gluten solids are 80-85% composed of proteins and various flour substances (lipids, carbohydrates, etc.), with which gliadin and glutenin react. Gluten proteins bind about half of the total amount of flour lipids. Gluten protein contains 19 amino acids. Glutamic acid predominates (about 39%), proline (14%) and leucine (8%). Gluten of different quality has the same amino acid composition, but different molecular structure. The rheological properties of gluten (elasticity, elasticity, extensibility) largely determine the baking value of wheat flour.

Rye flour proteins. According to the amino acid composition and properties, rye flour proteins differ from wheat flour proteins. Rye flour contains a lot of water-soluble proteins (about 36% of the total mass of protein substances) and salt-soluble (about 20%). The prolamin and glutelin fractions of rye flour are much lower in weight; they do not form gluten under normal conditions. The total protein content in rye flour is somewhat lower than in wheat flour (10-14%). Under special conditions, a protein mass can be isolated from rye flour, resembling gluten in elasticity and extensibility.

Carbohydrates

The carbohydrate complex of flour is dominated by higher polysaccharides (starch, fiber, hemicellulose, pentosans). A small amount of flour contains sugar-like polysaccharides (di- and trisaccharides) and simple sugars (glucose, fructose).

Starch. Starch, the most important carbohydrate in flour, is contained in the form of grains ranging in size from 0.002 to 0.15 mm. The size, shape, swellability and gelatinization of starch grains are different for different types of flour. The size and integrity of starch grains affects the consistency of the dough, its moisture capacity and sugar content. Small and damaged grains of starch are saccharified faster in the process of making bread than large and dense grains.

Cellulose. Cellulose (cellulose) is located in the peripheral parts of the grain and therefore is found in large quantities in flour of high yields. Wholemeal flour contains about 2.3% fiber, and wheat flour of the highest grade contains 0.1-0.15%. Fiber is not absorbed by the human body and reduces the nutritional value of flour. In some cases, a high fiber content is useful, as it accelerates the peristalsis of the intestinal tract.

Hemicelluloses. These are polysaccharides belonging to pentosans and hexosans. In terms of physicochemical properties, they occupy an intermediate position between starch and fiber. However, hemicelluloses are not absorbed by the human body. Wheat flour, depending on the variety, has a different content of pentosans - the main component of hemicellulose.

Flour of the highest grade contains 2.6% of the total amount of grain pentosans, and flour of the II grade contains 25.5%. Pentosans are divided into soluble and insoluble. Insoluble pentosans swell well in water, absorbing water in an amount exceeding their mass by 10 times.

Soluble pentosans or carbohydrate mucus give very viscous solutions, which, under the influence of oxidizing agents, turn into dense gels. Wheat flour contains 1.8-2% of mucus, rye flour - almost twice as much.

Lipids. Lipids are called fats and fat-like substances (lipoids). All lipids are insoluble in water and soluble in organic solvents.

Fats. Fats are esters of glycerol and high molecular weight fatty acids. Wheat and rye flour of various varieties contains 1-2% fat. The fat found in flour has a liquid consistency. It consists mainly of glycerides of unsaturated fatty acids: oleic, linoleic (mainly) and linolenic. These acids have a high nutritional value, they are credited with vitamin properties. Hydrolysis of fat during storage of flour and further conversion of free fatty acids significantly affect the acidity, taste of flour and the properties of gluten.

Lipoids. Flour lipoids include phosphatides - esters of glycerol and fatty acids containing phosphoric acid combined with some nitrogenous base.

The flour contains 0.4-0.7% of phosphatides belonging to the group of lecithins, in which choline is the nitrogenous base. Lecithins and other phosphatides are characterized by high nutritional value and are of great biological importance. They easily form compounds with proteins (lipo-protein complexes), which play an important role in the life of every cell. Lecithins are hydrophilic colloids that swell well in water.

Pigments. Fat-soluble pigments include carotenoids and chlorophyll. The color of carotenoid pigments in flour is yellow or orange, and chlorophyll is green. Carotenoids have provitamin properties, as they are able to turn into vitamin A in the animal body.

Minerals

Flour consists mainly of organic substances and a small amount of mineral (ash). The mineral substances of the grain are concentrated mainly in the aleurone layer, shells and embryo. Especially a lot of minerals in the aleurone layer. The content of minerals in the endosperm is low (0.3-0.5%) and increases from the center to the periphery, so the ash content is an indicator of the flour grade.

Most of the minerals in flour consist of phosphorus compounds (50%), as well as potassium (30%), magnesium and calcium (15%).

In negligible amounts contains various trace elements (copper, manganese, zinc, etc.). The iron content in the ashes of different types of flour is 0.18-0.26%. A significant proportion of phosphorus (50-70%) is presented in the form of phytin - (Ca - Mg - salt of inositol phosphoric acid). The higher the grade of flour, the less minerals it contains.

Enzymes

Cereal grains contain a variety of enzymes, concentrated mainly in the germ and peripheral parts of the grain. In view of this, high-yield flour contains more enzymes than low-yield flour.

Enzyme activity in different batches of flour of the same variety is different. It depends on the conditions of growth, storage, modes of drying and conditioning of the grain before grinding. Increased activity of enzymes was noted in flour obtained from unripe, sprouted, frost-bitten or bug-damaged grain. Drying grain under a hard regime reduces the activity of enzymes, while storing flour (or grain) it also decreases somewhat.

Enzymes are active only when the humidity of the environment is sufficient, therefore, when storing flour with a moisture content of 14.5% and below, the action of enzymes is very weak. After kneading, enzymatic reactions begin in semi-finished products, in which hydrolytic and redox flour enzymes participate. Hydrolytic enzymes (hydrolases) decompose complex flour substances into simpler water-soluble hydrolysis products.

Wholemeal flour has a lower digestibility and energy value, but a high biological value, it contains more vitamins and minerals.

Flour of the highest grades poorer in useful substances, since they are concentrated mainly in the shells of the grain and the germ, which are removed when flour is obtained, but is absorbed more easily and more completely.

flour 2nd grade obtained from soft wheat. The color is white with a yellowish-gray tint. Flour differs by the content of 8-10% shells, flour particles are larger than in the 1st grade, heterogeneous in size. Gluten content - not less than 25% ash content - not more than 1.25%. Flour of the 2nd grade is used in baking bread.

Whole flour is made from soft wheats with single-sorted wholemeal grinding without screening out bran. Flour yield - 96% Grayish-white color, gluten content - 20%, ash content, up to 2%. Used for baking bread.

Nutritional and energy value.

We consider the nutritional and energy value of flour in the form of a table

Table 1

				Carbohydrates
Buckwheat flour
Corn flour (dietary)
Wheat flour 1st grade
Wheat flour 2nd grade
Wheat flour
Whole wheat flour
Peeled rye flour
Rye flour
Rice flour (diet)
Wheat bran

Factors that shape the quality of flour.

Raw material.

The flour milling industry of our country produces five varieties

wheat flour and three grades of rye bread flour.

Grain - 10% Seeded - 63%

Premium - 30% Peeled - 87%

First grade - 72% Wallpaper - 95%

Second grade - 85%

Wallpaper - 96%

In addition, two varieties of wholemeal flour are prepared from a mixture of wheat and rye: wheat-rye and rye-wheat. The flour production process consists of preparing grain for grinding and grinding itself. Wholemeal flour is obtained by grinding the whole grain as a whole, other varieties (varietal flour) are prepared from endosperm with a small admixture of shells. Accordingly, grindings are divided into wallpaper (simple) and varietal (complex). Varietal grinding, depending on the amount of flour obtained from one batch, can be one-, two- and three-varietal.

The resulting amount of flour of each grade must correspond to the established rate of its output (the output is the amount of flour, expressed as a percentage of the mass of processed grain with a basic moisture content of 14.5%). Individual batches of grain have different quality indicators. To obtain flour of standard quality, batches of grain are sorted at the mill - they are made up of a grinding mixture. At the same time, moisture, ash content, color, vitreousness, gluten and other indicators of grain are taken into account. Preparation of grain for grinding consists in removing impurities, cleaning the surface of the grain and conditioning the grain mass. Weed and grain mixture is removed using special grain cleaning machines, metal impurities are removed on magnetic separators.

Flour production technology.

Flour mills are equipped with warehouses and elevators for grain, warehouses for storing finished products. The production process is completely mechanized. The principle of gravity is widely used in the technological process. Grain or intermediate products, lifted to the top floor by mechanical (noria) or pneumatic transport, enter the machines with the help of distributing devices and then go through gravity (gravity) pipelines to the machines located on the floor below.
To obtain flour of standard quality, the grain is cleaned and conditioned before grinding. Grain is prepared in two stages. The first stage is the cleaning of grain from weed impurities in separators, trieres, duaspirators; extraction of mineral impurities in stone-separating machines; washing of grain in washing machines and its conditioning in silos. The second stage is additional cleaning of grain in separators, duaspirators, brush machines, moisturizing in moisturizing machines and softening.
From the grain cleaning department, the grain enters the grinding department, where roller machines are located. The process in which the grain gradually unfolds and crumbles out of it, consisting of endosperm with fused shells, and the endosperm is partially crushed to a state of flour, is called tattered. This process involves four to six systems of rolling machines (I torn, II torn, etc.). The larger the system number, the finer the grooves at the rollers and the thinner the gap (the distance between the rollers). The products formed after each tearing system have different sizes and unequal endosperm content. The following products are obtained: flour, semolina (fine, medium and large), dunsta (medium between flour and small semolina). For separation by size, they are sent to screening machines (sieving). Next, grits and dunsts go to sieve machines, sorting them by quality. The sieving machines sort the products using tilted reciprocating sieve frames and air flow through the sieves and products. The most solid products, containing mainly endosperm, are sent to roller machines, where they are ground into flour. Grits and dunst are ground during successive grinding with sifting of finished flour in grinding roller machines. This process is called grinding. Grits with particles of the shell are sent to grinding roller machines equipped with rollers without corrugations, then again for sorting and sieving into sieve machines. The process of processing grains containing shells is called grinding.
All the flour obtained from the working sifters goes to the control ones (to prevent the ingress of foreign objects, grain shells, etc.). After control screenings, the flour is transferred to a bulk storage warehouse or packed in bags. To increase the nutritional value, vitamins B1, B2, and PP are added to the flour of the highest and first grades. The technological process at the flour mill is accompanied by the release of dust. To capture it, an aspiration system is used. At a certain concentration in the air, grain and flour dust are explosive.

Technological defects and marriage.

The reason for the occurrence of defects in flour may be the use of low-quality grain, violation of manufacturing technology, non-compliance with modes and periods of storage. Self-heating of flour is an increase in temperature in its mass due to internal physiological processes and poor thermal conductivity. Among the physiological processes that occur in cereals and flour during self-heating, it is necessary to single out the process of respiration and the development of microorganisms. At the same time, the organoleptic indicators of flour (color, smell, taste) change. The foreign smell of flour occurs due to non-observance of the commodity proximity of their storage with products that tend to transmit smell (fish, spices, soap, cologne, etc.). The reason for the appearance of an extraneous taste in these products may also be extraneous aromatic impurities in the grain before its processing.

With prolonged storage, especially in the light, the flour becomes discolored, darkens. Wetting flour is the cause of other defects. Such products cannot be stored for a long time, they quickly deteriorate. The increased humidity of flour activates enzymes, increases the intensity of their respiration, self-heating, and the development of microorganisms. Moldy flour occurs due to self-heating or storage in poorly ventilated rooms with high relative humidity - above 80%. Products acquire a musty smell, acidity increases in them, their color becomes darker. Moldy flour clumps.

Flour souring begins in the inner layers of the product mass due to the development of acid-forming bacteria, primarily lactic acid bacteria. Souring occurs to a greater extent in flour and cereals. Rancidity in flour is the result of fat oxidation.

Flour with a high fat content will go bitter faster. Flour of the lower grades contains more particles of the germ rich in fats, so it will also go bitter faster. A decrease or loss in the flowability of cereals occurs with an increase in contamination in them, and in flour (in particular of lower grades) due to the large content of shell particles. This also happens at high humidity. The ability of flour to lose flowability partially or completely is called compaction or caking.

Caking is more characteristic of flour. With an increase in the duration of storage, the likelihood of flour caking increases. Flour that has lost its flowability due to the pressure of the upper layers of products on the lower ones is not used for long-term storage. If the flour is compacted and loses its flowability due to self-heating, the development of microorganisms and pests of grain stocks, it becomes unsuitable for consumption and is not allowed for sale. Flour with low baking properties is defective, for example, flour with a low gluten content and its low quality.

Factors Preserving Flour Quality

Packaging and labeling.

Flour packaging - according to GOST 26791-89 regulates the requirements for the packaging of wheat and rye flour. Packed in consumer packaging with a net weight in kilograms: 1,000; 2,000 and 3,000 for flour. Permissible deviations of the net weight of individual packaging units should not exceed in percentage: 1.0.

Flour is packaged in transport containers in new or used fabric grocery bags in accordance with GOST 30090 and other regulatory and technical documentation that ensure the safety of products.

Bags must be at least:

Category 2 - for flour from soft vitreous wheat for pasta; durum wheat flour (durum) for pasta; flour of the second grade from durum wheat (durum); wheat crushed grits;

Whole wheat flour for local supply is packed in bags of at least category 4. When transported by mixed railway - water transport or with reloading from one track to another, the flour is packed in new or used bags of at least category 1

In accordance with GOST R 51074-2003 the manufacturer (seller) is obliged to provide the consumer with the necessary and reliable information about food products, ensuring the possibility of their correct choice. This standard regulates grain processing products and must contain the following information:

Product name (for example, for flour: rye, rice, barley, corn, buckwheat, baking wheat, pancake wheat, etc.);

Grade or number (if any);

Name and location of the manufacturer [legal address, including the country, and, if not the same as the legal address, address(es) of production(s)] and the organization in the Russian Federation authorized by the manufacturer to accept claims from consumers on its territory (if any);

Trademark of the manufacturer (if any);

Net weight;

Composition of the product (except for one-component products);

Food additives, flavors, biologically active food supplements, ingredients of non-traditional products;

For fortified wheat bread flour of the highest and first grades, the word "VITAMINIZED" (in large print);

The nutritional value;

date of manufacture;

Storage conditions;

Shelf life;

Shelf life for corn flakes, wheat, rice and oatmeal;

Designation of the document in accordance with which the product is manufactured and can be identified;

Information about confirmation of conformity.

The same information is applied to the labels attached to the bags.

Storage and transportation.

Flour storage is regulated in accordance with GOST 26791.

The shelf life of flour is set by the manufacturer of products at an ambient temperature not higher than 25 ° C and relative air humidity not higher than 70%.

Flour is stored in dry, well-ventilated, pest-free grain stocks, warehouses in compliance with sanitary rules approved in the prescribed manner.

The shelf life of deodorized soybean flour at a relative humidity of 60% is 12 months from the date of production.

Flour can be stored in unheated and heated warehouses. Long-term storage of flour is carried out in unheated warehouses, and the temperature in them depends on the season.

Flour intended for retail trade usually comes in bags. Each batch of product received for storage is placed in a separate stack. The bottom row of bags is placed on solid wooden underlays to prevent sweating from contact with the cold floor. The distance from the walls to the stack must be at least 0.5 m, and the passages between them must provide free access to each stack.

During long-term storage, the stack is shifted at least twice a year, always changing places of the upper and lower bags.

As a rule, stores store relatively small batches of flour, which ensure an uninterrupted supply of the population for 10-45 days. The temperature is preferably not higher than 10-18 °C. In stores, it is necessary to strictly monitor the commodity neighborhood, since flour easily absorbs odors.

Flour is transported both in bags and in bulk.

When transporting small batches of flour in bags, you can use ordinary flatbed trucks, while covering the bags with a tarpaulin on top. For the mass transportation of flour in bags, specialized road trains are used, the bodies of which are equipped with a lifting overturning metal top, attached to the sides with latches. Before loading and unloading, the bolts are removed from the side from which you want to open the body. The latches of the opposite side serve as the axis of rotation of the top of the body. To prevent the top of the body from closing spontaneously, a safety comb with a latch and a special lock are provided. The use of such road trains makes it possible to transport flour in bags behind the seal of the sender, completely eliminates the ingress of moisture on the bags and the spraying of flour during transportation. Such road trains can also be used for the transportation of granulated sugar and cereals in bags.

For bulk bulk transportation of flour, road trains - flour trucks are used. Flour is unloaded from the tank pneumatically, for which a compressor is installed on the chassis of the car behind the cab, which provides pressure. Compressed air from the compressor through the air duct system enters the discharge pipe, aeration box, installed inside the tank on the bottom closer to the discharge pipe, and into the upper part of the tank. The unloading capacity is 0.3-0.5 t/min. Thanks to the use of a pneumatic system, flour can be fed during unloading at a distance of up to 50 m and at a height of up to 25 m.

At the bakery, the road train is weighed and sent for unloading. The unloading pipe of the tank is connected to the inlet pipe of the transport pipeline of the factory silo, the compressor is turned on and compressed air is first supplied to the discharge pipe to purge the flexible pipeline, and then to the aeration box and the tank. Flour enters the discharge pipe, where it is picked up by a stream of air entering directly into the pipe and transported directly through the pipeline to the silo. The pressure gauge installed on the tank makes it possible to set the end of unloading. The use of flour trains provides a significant economic effect. The reduction in flour losses from spraying is about 3 kg for each transported ton. In addition, the use of flour trains significantly reduces the complexity of unloading and loading operations.

Implementation of flour.

The development trends of the flour-grinding sector of the European Union correspond to the world ones. Modern Russian mills meet all engineering requirements. A complex multifactorial technological process, the saturation of enterprises with technological and auxiliary equipment, automated control and management systems place increased demands on professional knowledge, organizational ability and the general cultural and intellectual level of process engineers. On the basis of modern technology, millers have reached a high level of realization of the technological potential of flour. The export of our flour to Europe is 60%. Further development is aimed at creating multifunctional circuits, reducing the process, reducing operating and energy costs. Market conditions dictate the expansion of the assortment, including special varieties: for dietary and baby food, for flour confectionery, etc.

Fake flour.

Flour is a relatively cheap product, so its assortment falsification is rare, mainly in market trade or small-scale wholesale delivery of flour by one-day firms.

At large flour mills, such cases are excluded, since along with in-house inspection control, which ensures the release of products of appropriate quality and assortment characteristics, the manufacturing organization risks losing the image of a reliable business partner and its market segment.

Assortment falsification of flour in modern conditions is carried out by mixing non-food substitutes, mainly sand or bran. The methods of assortment falsification known in pre-revolutionary Russia using chalk, lime, ash, and other types of flour are practically not used, since many of these falsifications are either inaccessible (for example, ash), or differ little from wheat flour in price (for example, prices wheat, rye, corn, barley flour, gypsum and chalk are about the same), or are easily detected when rubbed between fingers (lime). In addition, when adding chalk, gypsum, lime, a fake is easy to detect by adding acid to the aqueous suspension of flour. In the presence of these alkaline substitutes, they interact with acid and rapidly release carbon dioxide (C0 2). Qualimetric falsification is carried out by partial or complete replacement of the lowest grade flour with the highest, as well as the addition of bran. To give the necessary white color, the flour is bleached.

The method of high-quality falsification of flour described by I.P. Chepurny by introducing food additives into products in retail sales is not used, and the use of technological food additives to eliminate certain flour defects (low quality and quantity of gluten) to improve the quality of the finished product is not a falsification and does not require mandatory communication to consumers of all the features of the technological process.

Quantitative falsification takes place during the sale of packaged flour in a retail network. In addition, similarly to grain, quantitative falsification of flour is possible when it is sold in whole packages (bags) without re-weighing and opening the package by underweighting or pouring river sand or other substitute on the bottom of the package.

Flour quality assessment.

Organoleptic indicators.

Determining the quality of flour by organoleptic indicators, their smell, taste, color, mineral impurities are taken into account.

Taste flour should be slightly sweet, without a bitter or sour taste. A pronounced sweet taste is not allowed, as it indicates that the flour was obtained from germinated grain. The rancid and sour taste of flour indicates that significant changes in the chemical composition have occurred in it. The bitter taste of flour is reported by wormwood seeds that have fallen into the grain during grinding.

Smell fresh flour - pleasant, weak. Moldy, musty and other smells are not allowed. Foreign odors can appear in flour due to various reasons. So, musty and moldy odors indicate the poor quality of the grain from which the flour is obtained, or the staleness of the flour. The wormwood and garlic smell of flour is given by admixtures of wormwood and garlic. When the flour is affected by the smut, a herring smell appears in it. Foreign odors can turn into flour during transportation and storage in contaminated bags, as well as in wagons in which there were strong-smelling products. Some smells disappear when the bread is baked, others are transferred to it. Flour that has any foreign flavors and odors is not allowed for sale and baking.

The presence of mineral impurities determined by chewing. The feeling of crunching on the teeth when chewing flour is caused by crushed mineral impurities (sand, pebbles, etc.), which get into the flour if the grain was poorly cleaned. The feeling of crunching on the teeth is not allowed.

Colour depends on the type and grade of flour. According to the standard, each type of flour must have a certain color. So, white or white with a creamy tint should have varieties of extra and higher flour for baking wheat and types M 45-23; M 55-23; MK 55-23 general purpose wheat flour. White or cream color with a yellowish tint is typical for baking grains, and white or white with a yellowish tint is for baking flour of the 1st grade, as well as general purpose flour M75-23; MK 75-23; M 100-25. The presence of a certain amount of shell particles in flour of the 2nd grade gives the white color a yellowish or grayish tint. The same color is typical for general-purpose flour M 125-20 and M 145-23. Whole-baking flour has a white color with a yellowish or grayish tint and clearly visible particles of grain shells. Higher grades of flour are always lighter, while lower ones are darker with the presence of shell particles. This makes it possible to quickly determine the grade of flour by comparing it with standards - samples of a certain grade. However, such a determination of the grade gives only an approximate result, since, in addition to the presence of shells, many other factors affect the color of the flour. Among them, the natural features of the grain are important: the content of pigments, the vitreousness of the endosperm, and even the mineral composition. The color of the flour also depends on the degree of grinding of the particles. So, fine flour, consisting of small particles, seems lighter than flour, consisting of larger particles that absorb light.

Physical and chemical indicators.

Moisture, whiteness, ash content, grinding size, quantity and quality of raw gluten (for wheat flour), the content of metal magnetic impurities, infection and contamination by pests of grain stocks are considered as physical and chemical indicators of flour. Moisture content of flour should not exceed 15.0%. This indicator is not only crucial for the storage of flour, but also affects the yield of bread. The whiteness of premium flour should not be lower than 54 conventional units of the device RZ - BPL, 1st - from 36 to 53, 2nd - 12-35. In wallpaper flour, it is not limited. The ash content of flour is an indicator of its grade. According to the requirements of the standards, it should not exceed,%: the highest grade - 0.55, the 1st - 0.75, the 2nd - 1.25, upholstery - 2.0%. The flour grinding size is of great technological importance, it is determined by sifting on the appropriate sieves. In baking, flour is valued, which has particles that are uniform in size and form it. In wheat flour, standards regulate the quantity and quality of raw gluten. The amount of gluten is determined by washing it manually or using a device, and the quality is determined by color, smell, elasticity, extensibility. The amount of raw gluten in premium flour should not be lower than 24%, 1st - 25, 2nd - 21, upholstery - 18%. The content of metal-magnetic impurities in flour cannot exceed 3 mg per 1 kg.

Infection of flour with pests of grain stocks is not allowed.

In flour, the permissible level of toxic elements (lead, cadmium, arsenic, mercury, copper, zinc), mycotoxins (aflatoxin B1, zearalenone, etc.), radionuclides and pesticides is normalized.

Chemical indicators. Humidity flour - an important indicator of its quality, determines the persistence of flour and its baking properties. The moisture content of flour should not exceed (in%): for rye and wheat - 15, soy - 9-10.

Ash content of flour characterizes the content of minerals in it. This indicator depends on the type of flour: the higher its grade, the lower the ash content. So, the ash content of wheat flour should be (in%, not more than): grains - 0.60, premium - 0.55, 1st - 0.75, 2nd - 1.25, wallpaper - 2.

size grinding characterizes the degree of grinding of flour. It is determined by sifting through silk sieves or wire mesh sieves with different mesh sizes. For example, for wheat flour it is allowed (in %).

Quantity and quality of raw gluten- an important indicator that determines the baking and pasta advantages of wheat flour. Gluten is an elastic mass formed from the swollen proteins of wheat flour when kneading dough from it. The amount of gluten in wheat baking flour should be (in%, not less than): in the highest grade - 28, in the 1st - 30, in the 2nd - 25, in the wallpaper - 20.

The quality of gluten is determined by color (light, gray, dark) and elasticity. With an increase in the gluten content in flour, such indicators of the quality of products from it as elasticity, looseness of the crumb and the volume of bread improve. Pasta improves surface condition, they become more durable.

Rye flour proteins do not form gluten.

Infection pests of grain stocks are not allowed. Content metal impurities should be no more than 3 mg per 1 kg of flour.

Safety indicators.

Safety requirements are stipulated by flour standards.

table 2

	The name of indicators	Metric Requirements
		not musty, not moldy
		not sour, not bitter
	The presence of mineral impurities	when chewed, there should be no crunch
	Metal-magnetic impurity, mg per 1 kg of flour; The size of individual particles in the largest linear dimension of 0.3 mm and (or) a mass of not more than 0.4 mg, no more
	Humidity, in %, not more than: flour from durum wheat and soft high vitreous wheat for pasta Flour for baby food (rice, buckwheat, oatmeal) For other types of flour
	Additional requirements for flour for baby food: Acidity, in degrees (0 T), not more than: buckwheat
	Acid number of fat in 100 gr. flour, mg KOH, no more

Conclusion.

In conclusion, I would like to say about the baking properties of flour. The baking properties of wheat flour are determined by the following indicators:

the color of flour and its ability to darken in the process of making bread;

structural-mechanical (rheological) properties of dough or raw gluten (flour strength) and the degree of their change in the process of testing;

water absorption capacity, i.e. the amount of water that is necessary to form a dough with optimal structural and mechanical properties;

gas-forming ability, i.e., the ability of flour to form during the fermentation of the dough (for a certain period) one or another amount of carbon dioxide;

autolytic activity, i.e., the ability to decompose complex flour substances into simpler water-soluble products under the action of flour's own enzymes.

The baking properties of rye flour are mainly determined by the state of its carbohydrate-amylase complex. Rye flour starch is less resistant to heat and hydrolytic processes than wheat starch.

Rye starch gelatinizes already at a temperature of 55 ° C; gluten starch is easily hydrolyzed by amylolytic enzymes.

Rye flour, even obtained from grain of normal quality, unlike wheat flour, contains active a-amylase, which causes starch dextrinization during bread baking. The grain of rye germinates more easily than the grain of wheat, and the autolytic activity at the same time reaches a value dangerous for the quality of bread. The crumb of rye bread with an increased content of dextrins becomes sticky, often there is a seal in it, voids appear. The crust of bread made from flour with high autolytic activity is dark, with cracks and undermining. Sometimes the crust lags behind the crumb.

To assess the baking properties of rye flour, autolytic activity is determined, since it characterizes the state of the carbohydrate-amylase complex, on which these properties depend.

The autolytic activity of rye and wheat flour is determined by the following methods: by autolytic test; by changing the viscosity of the water-flour suspension in various ways.

The autolytic activity of flour is expressed as the percentage of water-soluble substances in terms of the dry matter of the flour. The content of water-soluble substances is measured after heating the water-flour suspension under certain conditions favorable for the action of hydrolytic enzymes. The water-soluble substances formed in this case consist of dextrins, as well as products of protein hydrolysis and other complex flour substances.

The Hagberg method, which determines the falling number (viscosity index), is widely used in many countries to assess the autolytic activity and baking properties of flour.

The higher the autolytic activity of the flour, the lower the viscosity of the suspension and, accordingly, the lower the value of the falling number (in seconds). For rye wholemeal flour, the falling number must be at least 105 s, for peeled flour - 155 s.

The baking properties of rye flour also depend on the state of the protein-proteinase complex. The structure of protein substances and their hydrophilicity affect the viscosity of rye dough, but this dependence has not been studied enough. Significantly increase the viscosity of the dough carbohydrate mucus, the content of which in rye flour is significant. However, the effect of proteins and pentosans on the baking properties of flour has not been precisely established.

Bibliography.

Gavrichenkov D.N., Economics, organization and planning of flour and cereal production, M., 1957.

Gerasimova V.A. Commodity science and expertise of flavoring goods textbook for university students / V.A. Gerasimova, E.S. Belokurova, A.A. Vytovtov. - St. Petersburg [and others]: Peter, 2005. - 396 p.: ill.

Zharikova G.G. Microbiology of food products. Sanitation and hygiene: a textbook for students studying in the specialty "Commodity science and examination of goods" / G.G. Zharikov. - Moscow: Academia, 2005. - 299 p.

Kazantseva N.S. Merchandising of food products: Textbook. - M.: Publishing and Trade Corporation "Dashkov and K0". - 2007. - 400 p.

Kondrashova E.A., Konik N.V., Peshkova T.A. Merchandising of food products: Textbook. - M.: Alfa-M: INFRA-M, 2007. - 416 p.

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Appendix.

Appendix 1

Quality indicators of wheat baking flour

Flour grade						Grinding size, %
								Passage through a sieve according to GOST 4403
					Not below the second group
						5 in N43 silk fabric or N45/50 polyamide fabric PA
Krupchatka	White or cream with a yellowish tint					2 of silk fabric N23 or polyamide fabric N21 FC-150		No more than 10.0 of N35 silk fabric or N36/40 polyamide fabric PA
					Not below the second group	2 in N35 silk fabric or N36/40 polyamide fabric PA		Not less than 80.0 N43 silk fabric or N45/50 polyamide fabric PA
	White with a yellowish or grayish tinge					2 in N27 silk fabric or N27 polyamide fabric		Not less than 65.0 of silk fabric N38 or polyamide fabric N41/43 PA
	White with a yellowish or grayish tinge with noticeable particles of grain shells	Not less than 0.07% lower than the ash content of grain before cleaning, but not more than 2.0%						Not less than 35.0 of silk fabric N38 or polyamide fabric N41/43 PA

Annex 2

Quality indicators of wheat flour of general purpose

		Mass fraction of ash in terms of dry matter,%, no more	Whiteness, conventional units of the RZ-BPL device, not less than	Mass fraction of crude gluten, %, not less than	The quality of raw gluten, conventional units of the device idc	Grinding size, %			Number of fall, "PE", s, not less than
						The rest on a sieve in accordance with GOST 4403, no more	Residue on a wire mesh sieve according to ND, no more	Passage through a sieve according to GOST 4403, not less than
	White or creamy white				Not below the second group
						5 made of silk fabric N43 or polyamide fabric N 45/50 PA
	White or white with a yellowish tint					2 made of silk fabric N35 or polyamide fabric N 36/40 PA		80.0 of silk fabric N43 or polyamide fabric N 45/50 PA
	White or white with a yellowish tint					2 made of silk fabric N27 or polyamide fabric N27 PA-120		65.0 in silk fabric N38 or polyamide fabric N41/43 PA
	White or white with a yellowish tint					2 made of silk fabric N27 or polyamide fabric N27 PA-120		65.0 in silk fabric N38 or polyamide fabric N41/43 PA
	White with a yellowish or grayish tint					2 of silk fabric N27 or polyamide fabric N27 PA-120		65.0 in silk fabric N 38 or in polyamide fabric N 41/43 PA
								50.0 N38 silk fabric or N41/43 polyamide fabric PA
Note - The indicator "whiteness" of flour is valid instead of the indicator "ash content" at enterprises equipped with laboratory instruments and equipment in accordance with GOST 26361.