Commodity characteristic of flour - abstract. Nutritional value, chemical composition of wheat and rye flour Composition and nutritional value of flour

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.

Wheat flour of the highest grade included in the list of the most popular varieties among consumers. It stands out for its nutritional qualities. Due to the fact that flour is obtained by applying fine grinding, if you rub it with your fingers, the presence of grains is not felt at all. Flour of this kind is similar to powder or dust. Outwardly, a quality product stands out for its white color, although the presence of a pale beige tint is still allowed. Since there is little gluten in high-grade flour, pastries made on its basis increase in size and acquire a lush texture.

Beneficial features

The benefits of wheat flour of the highest grade are at a low level, since almost all substances important for the body contained in the grain are removed from it. Due to the presence of a large amount of starch, products made from such flour supply the body with energy. It contains a small amount of B vitamins, which are important for the normal functioning of the nervous system. Useful substances are not destroyed after heat treatment. The composition of wheat flour of this variety includes potassium, which, together with sodium, ensures the transmission of impulses in the nervous system. It also contains magnesium, which is important for the heart muscle.

Use in cooking

A large number of confectionery products and various types of bread are prepared from wheat flour of this grade, for example, buns, cakes, cakes, pies, etc. This flour is ideal for making various types of dough, from which you can create many different culinary masterpieces. You can also prepare a large number of thick sauces and dressings on its basis.

Harm of wheat flour of the highest grade and contraindications

Premium wheat flour can harm people, especially those who abuse products made from it, and this can lead to weight gain. You should be careful with such pastries also with diabetes.

Nutritional value and composition of flour

Flour contains a large amount of B, PP, H, E vitamins, and the chemical composition is rich in almost all minerals necessary for the normal development of the body:

• potassium, calcium, sodium, magnesium, iron, phosphorus;
• chlorine, aluminum, titanium, nickel, tin;
• iodine, copper, chromium, molybdenum, zinc, boron, selenium, etc.

I would like to note that there are practically no vitamins in the highest grades of flour, but low grades contain the whole complex of vitamins and microelements.

Flour from ancient times to today is one of the staple foods in every kitchen, from which the hostess can prepare many varieties of dishes. Flour of the first grade contains no more than 3-4% of the grain shell. This is the most beloved and widespread variety of the product. It is white with a yellowish tinge. It contains a third of gluten, it makes wonderful rich and not rich pastries that do not get stale for a long time.

Variety and types of flour

Wheat flour is divided into different grades, according to the grinding size.

This is the most common type of flour, from which housewives prepare many dishes and pastries. Flour of the first grade is white in color with a yellowish tint. This type of flour contains starch - 75%, protein - 15%, raw gluten - 30%, sugar - 2%, fat - 1%, fiber - 3%. The composition of this flour contains vitamins PP, H, B1, B12, B2, B9, and the mineral composition contains zinc, chlorine, magnesium, sodium, iron, sulfur.

100g of flour of the 1st grade contains:

• Water - 14.
• Proteins - 10.6.
• Fats - 1.3.
• Carbohydrates - 73.2.
• Kcal - 329.

First-grade flour is well suited for baking pancakes, pies, rolls, etc., but not very good for high-quality breads and confectionery products (high-grade flour is needed for these purposes).

The flour of this variety contains bran and crushed grain shells: gluten - 25%, starch - 70%, protein - 15%, sugar - 2%, fat - 2%, fiber - 0.7%. The color of this type of flour is from yellowish to gray and brown. Baking from this flour is fragrant, porous, but not lush. Gingerbread and cookies are made from it. Also, second-grade flour is suitable for pancakes, dumplings, dumplings and baking dietary bread with the addition of rye flour. Flour of the 2nd grade contains more vitamins and microelements. These are vitamins of groups B, H, E, A, and the chemical composition includes:

• magnesium, potassium, iron, sulfur, phosphorus;
• zinc, vanadium, manganese, molybdenum, copper, chromium, cobalt.

100g of flour of the 2nd grade contains:

• Water - 14.
• Proteins - 11.7.
• Fats - 1.8.
• Carbohydrates - 70.8.
• Kcal - 328.

Baking from flour of the 2nd grade is much healthier and richer in vitamins and microelements than flour of the 1st grade.

Favorite variety of housewives. Baking from it is lush, soft, tasty. It has more fat and almost no starch. The color of this type of flour is snow-white. Flour contains proteins - 10%, crude gluten - 28%, fiber - 0.15%, fat - 0.15%, sugar - 0.15%. There are fewer vitamins than in previous varieties: vitamins B1, B2, B9, PP, a little E and A. Microelements contain potassium, sodium, magnesium, phosphorus, sulfur, molybdenum, chlorine.

100g of premium flour contains:

• Water - 14.
• Proteins - 10.3.
• Fats - 0.9.
• Carbohydrates - 74.2.
• Kcal - 327.

Premium flour is ideal for culinary products, puff, shortcrust and yeast dough.

Flour

It has a light cream color and a high percentage of gluten. Possesses high baking properties. This type of flour is used for yeast dough with a high content of sugar and fat (buns, Easter cakes). Products from this type of flour have poor porosity and quickly become stale.

Wheat flour

Coarse and heterogeneous in particle size. Flour contains raw gluten - 20%, has a high sugar-forming capacity and moisture capacity. This type of flour is used for baking table breads.

The benefits and harms of eating flour

Benefit. The use of flour speeds up the metabolism, protects the cardiovascular system, stimulates the brain, stimulates the production of estrogen, helps to cure Alzheimer's disease, osteoporosis. The use of this product reduces the risk of gallstones.

Flour helps in the treatment of asthma, bronchitis, prevents the formation of free radicals. The ingredients that are part of the flour soften the inflammatory processes in the human body.

Harm. Flour is a high-calorie product, so its excessive consumption can cause obesity, high blood pressure and allergies.

Reasonable use of products based on flour will bring true pleasure in taste and aroma. After all, traditional tea drinking is never complete without flour-based products, and there are a lot of them: for all tastes and preferences.

I couldn't fit everything in one post, so I had to split it into two parts. Start and we will continue.

Flour composition.
The baking properties and nutritional value of a particular type of flour directly depend on the chemical composition. For example, premium wheat flour is produced from the central layers of the grain endosperm, so it contains a maximum of starch, but a minimum of proteins, fats, sugars, minerals and vitamins.

The table shows the average composition of wheat and rye flour, depending on the variety:

Carbohydrates.
The first place, both in rye and wheat flour, is occupied by carbohydrates (starch, sugars, pentosans, cellulose) and proteins, the quality of the future dough directly depends on their properties. It is proteins that determine the strength of wheat flour in other countries: the more protein (proteins) in flour, the stronger it (flour). In Russia, the strength of flour is defined differently, but more on that in the next post, but for now let's focus on the composition of flour.

Flour contains a variety of carbohydrates, the most important of which is starch. Starch in flour is contained in the form of grains, of various shapes and sizes, depending on the type and type of flour. The inner part of the starch grain consists of amylose polysaccharide, consisting of linear or slightly branched chains of glucose molecules connected by bonds between the 1st and 4th carbon atoms. The outer part of the starch grain is made up of amylopectin, a polysaccharide with tighter bonds of glucose. Therefore, in fact, it is the outer shell of the starch grain. The quantitative ratios of amylose and amylopectin in the starch of various cereals are 1:3 or 1:3.5. In hot water, amylopectin swells and amylose dissolves.

Starch determines many qualities of the future dough. Due to starch carbohydrates, dough is fermented under the action of enzymes. It is starch carbohydrates that are food for yeast, the waste product of which is carbon dioxide, loosening the dough and giving everyone's favorite holes in the baguette. In addition, starch absorbs up to 80% of the water in the dough, having a major influence on the formation of the dough. During the baking process, it is the starch that is responsible for the rise of the loaf, since when heated, the starch grains that absorb hot water swell, increase in volume, becoming more friable, thereby more susceptible to the action of amololytic enzymes. It is starch, as the main “jailer” of water in the dough, that is responsible for the hardening of the finished bread, as it is subject to syneresis over time - a spontaneous decrease in volume, due to the compaction of the starch paste (what it carries, my God). By the way, the process of swelling of starch grains in hot water is called gelatinization. Anyone who glued wallpaper at school knows what I'm talking about.

Squirrels.
Proteins are organic macromolecular compounds consisting of amino acids. In a protein molecule, amino acids are linked together by peptide bonds. The composition of wheat and rye flour proteins includes simple proteins (proteins), consisting only of amino acid residues, and complex proteins (proteins).

The technological role of flour proteins in the preparation of bread is great. The structure of protein molecules and the physicochemical properties of proteins determine the properties of the dough, affect the shape and quality of bread. Proteins have a number of properties that are especially important for making bread. The content of proteins in wheat and rye flour ranges from 9 to 26%, depending on the type of grain and its growing conditions. Proteins are characterized by many physicochemical properties, of which the most important are solubility, the ability to swell, to denature and hydrolyze - Wikipedia will help you, friends.

The more proteins are contained in the flour and the stronger their ability to swell, the more raw gluten will be obtained, namely the presence of gluten in Russia determines the strength of the flour. A significant part of flour proteins does not dissolve in water, but swells well in it. Proteins swell especially well at a temperature of about 30 ° C, while absorbing water 2-3 times more than their own weight. - the task of proteins, in general. When heated above 60 ° C, irreversible denaturation of proteins occurs - a change in the structure of the protein - proteins lose their ability to dissolve and swell and fold, forming a strong frame that determines the shape and volume of bread.

Rye flour proteins differ in composition and properties from wheat proteins. About half of rye proteins are soluble in water or salt solutions. Rye flour proteins have a greater nutritional value than wheat proteins (they contain many essential amino acids), but their technological properties are much lower. Protein substances of rye do not form gluten. In rye dough, most of the proteins are in the form of a viscous solution, so rye dough lacks the elasticity and elasticity characteristic of wheat dough.

Cellulose, hemicelluloses, pentosans are included in the group of dietary fibers. Dietary fibers are found mainly in the peripheral parts of the grain and therefore they are most abundant in high-yield flour. Dietary fiber is not absorbed by the human body, so they reduce the energy value of flour, while increasing the nutritional value of flour and bread, as they accelerate intestinal motility, normalize lipid and carbohydrate metabolism in the body, and contribute to the removal of heavy metals.

Fats.
Fats are esters of glycerol and higher fatty acids. The composition of flour fats includes mainly liquid unsaturated acids (oleic, linoleic or nolenic). The fat content in different varieties of wheat and rye flour is 0.8-2.0% per dry matter. The lower the grade of flour, the higher the fat content in it. Any fat in the dough slows down the fermentation process, this must be taken into account when you calculate the amount of yeast, butter and other muffins in the dough, when converted to the amount of flour. More yeast is put into sweet dough than bread dough, or special yeast is used, with strains grown specifically for baking.

And the last one for today - enzymes.
Enzymes are substances of protein nature that can catalyze (accelerate) various reactions.
The grain contains a variety of enzymes, concentrated mainly in the germ and peripheral (marginal) parts of the grain. Therefore, lower grade flour contains more enzymes than higher grade flour.
Enzymes are active only in solution, therefore, when storing dry grain and flour, their action is almost not manifested. After kneading semi-finished products, many enzymes begin to catalyze the decomposition reactions of complex flour substances. The activity with which the complex insoluble substances of flour are decomposed into simpler water-soluble substances under the action of its own enzymes is called autolytic activity (autolysis - self-decomposition).

Over time, the activity of enzymes does not stop, thereby explaining the meaning of my favorite long-term fermentation of the dough. With prolonged fermentation, due to the action of enzymes, the rheological properties of the dough are improved, which entails the baking of better and tastier bread.

The autolytic activity of flour is an important indicator of its baking properties. Both low and high autolytic activity of flour adversely affect the quality of dough and bread. It is desirable that the autolytic process of decomposition of proteins and dough starch occurs at a certain, moderate rate. In order to regulate autolytic processes in the production of bread, it is necessary to know the properties of the most important flour enzymes that act on proteins, starch and other flour components. But for this you need a whole chemical laboratory, and where to get it.

What remains for us after that is to try, try and try again. Find for yourself that grade and type of flour, products from which suit us, as a consumer of bakery products.

Bread is Peace. To know the processes that take place during the preparation and baking of bread is to know the whole world. Which is what I want for everyone.

Next time we will talk about the baking properties of wheat and rye flour.
And for today - everything!

The post was prepared on the basis of the materials presented in the book by T.B. Tsyganova "Technology of bakery production", sites http://muka.ucoz.ru and http://www.russbread.ru, as well as own conclusions and observations of the author-plagiarist.

List of recommended reading literature:
1. Tsyganova Tatyana Borisovna "Technology of bakery production". Textbook. 2002.
2. Auerman Lev Yanovich "Technology of bakery production". Textbook. Edition 9. 2005.
3. Sarychev Boris Georgievich "Technology and biochemistry of rye bread". 1959

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 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 storage of bread, starch paste undergoes aging (syneresis), which is the main cause of 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 is 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, the initial stage of proteolysis occurs in dough prepared from flour of normal quality without any 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. α-Amylase cleaves off the 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 tortoise bug, where proteolysis is intensive, has a high browning ability (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.