Flour production technology and stages of wheat grain preparation

Flour — a powdered product obtained by grinding grain, with or without the removal of bran.

The main raw material for flour production is wheat grain — 80% of flour is produced from wheat, and about 8% from rye. Grain of other crops is used for flour processing, but its amount is generally insignificant.

Milling wheat yields products such as semolina and flour (whole-grain and grade-specific).

Whole-grain flour — grain almost completely ground to a specified particle size, used for baking purposes.

Grade-specific flour — endosperm ground to a certain particle size with some inclusion of seed coats, used for baking and confectionery purposes, as well as for the production of pasta.

To obtain high-quality flour, thorough grain preparation is necessary, which includes the following operations:

• Formation of the milling batch — allows for the processing of lower-quality grain, from which it would be impossible to produce high-quality flour on its own. The batch is formed either in elevators or directly in the preparation departments of flour mills.
• Cleaning grain from impurities — impurities contained in the grain mass impair the quality of the produced flour. Therefore, when preparing grain for milling, it is necessary to remove the bulk of impurities, using their differences in physical properties from the grain. Impurities can differ from grain by: size, length, density, shape, and aerodynamic properties.
• Cleaning the grain surface — there is always dust and adhering dirt on the surface of the grain, especially in the crease, which is not removed by grain cleaning machines and must be gotten rid of.
• Hydrothermal processing of grain — treatment with water and heat. There are several methods of conditioning (cold, hot, and rapid).
• Grain grinding — simple and selective grinding are distinguished. In simple grinding, the goal is to grind the entire product uniformly to a certain particle size. In selective grinding, the least durable parts are primarily targeted.
• Sorting of ground products — fine particles represent finished flour, which should be separated and directed to the appropriate grade. Other fractions differ from each other not only in size but also in quality, i.e., in the content of endosperm and seed coats.

Flour is packed into clean, dry, odor-free sacks not infested with storage pests, with a net weight of 70 kg. A marking label made of paper or cardboard is attached to each sack, indicating the name of the product, its type and grade, net weight, production date, and standard number.

Flour enters the retail network packaged in paper single-layer bags with a net weight of 1-3 kg. The bags of flour are packed into crates.

Flour is stored in clean, dry premises at a temperature not exceeding "plus" 15°C and relative humidity of the air 60-75%. Sacks are placed on dunnage or pallets.

As a result of storage, various changes occur in flour — maturation, self-heating, and molding. During storage, commercial compatibility should be strictly observed, as flour cannot be stored together with or near pungent goods.

Rye flour — quite common, has its own features and advantages compared to wheat flour: it contains 30% more iron and twice as much magnesium and potassium. It has less starch and more dietary fiber; it improves metabolism and is beneficial for the stomach.

Grade classification of rye flour:

• Top grade (sifted rye flour) — suitable for any delicate baking.
• Third grade (peeled rye flour) — makes strong kvass.

Buckwheat flour — very nutritious, rich in carbohydrates, all eight essential amino acids, and almost all B vitamins; it is an excellent source of plant protein. It is known for its cholesterol-lowering properties and helps to get rid of mild depression. It is used to make certain types of pasta and noodles, and for baking muffins, waffles, and cakes.

Corn flour — used to prepare shortcrust and choux pastries, puddings, and added to sponge cake batter to make it more crumbly. It contains a minimum of proteins, so to make the dough elastic and fluffier during fermentation, more yeast must be added than to wheat flour dough. However, corn flour and products made from it cannot be stored for long, as they begin to turn bitter.

Rice flour — its main component is starch. Therefore, pastries made from rice flour are easily digested by the body. It is also used as a thickener for sauces. However, it is not sufficiently suitable for yeast dough.

Soy flour — produced from roasted soybeans ground into a powder. An excellent source of protein, iron, vitamin B, and calcium. Contains components that help activate the cardiovascular system.

Bread is one of the staple foods for mass consumption. By consuming 400-500 g of bread daily, a person satisfies their energy needs by 30-38%.

Raw materials used in bread making are divided into two categories:

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Preparation of raw materials: flour of different quality is mixed to provide better baking qualities. Flour is sifted and passed through magnetic separators, whereby it is saturated with air necessary for the vital activity of yeast. Salt and sugar are dissolved in water and filtered.

The dough is kneaded by dough-mixing machines for 6-9 minutes. During this process, proteins and starch swell, which gives the dough extensibility and elasticity.

Wheat dough is prepared in two ways:

1. Direct method: all raw materials provided by the recipe are taken, the dough is kneaded and left for 4-5 hours for fermentation.
2. Sponge method: first, a sponge is prepared and then the dough is made from it. The sponge is a liquid dough intended for yeast propagation. To prepare the sponge, half of the total amount of flour, 2/3 of the water, and all the yeast are taken, mixed, and left for 3-4 hours for fermentation. The dough is then kneaded on the finished sponge, adding the remaining amount of flour, water, and salt, and left for 1-1.5 hours for fermentation. With this method, the dough is of higher quality than with the direct method.

To prepare fluffy, porous bread, the prepared dough and sponge are left for several hours for fermentation at a temperature of 27-30°C. The number of yeast and lactic acid bacteria in the dough increases; during this period, alcohol, lactic acid, and carbon dioxide are formed. As it is released, carbon dioxide stretches the gluten, and by the end of fermentation, the dough acquires a porous structure. The dough increases 2-3 times in volume. For good aeration, the dough should not be too liquid or too dense.

Dough dividing is carried out by machines. The fermented dough is divided into pieces of a certain weight and volume. Pieces of dough weigh 6-15% more than finished products, since loss of mass occurs during baking and cooling.

The divided dough is sent to rounding machines, which give the pieces of dough the correct shape. Proofing of the divided dough is carried out in special chambers at a temperature of 35-40°C for 20-50 minutes. In the process of proofing, fermentation continues. The formed carbon dioxide aerates the dough and increases its volume.

Baking of bread is carried out at a temperature of 210-280°C for 10 to 80 minutes. At this time, the aerated dough is set in the form of a large number of bubbles in the gluten, forming the bread crumb. After baking, the bread is cooled. During the cooling period, moisture redistribution occurs in the bread: the humidity of the crust increases, and the crumb decreases.

The mass of bread obtained from 100 kg of flour and auxiliary raw materials used according to the recipe is called bread yield.

• Oat bread is rich in easily digestible fats, calcium, magnesium, and iron. It stimulates thyroid function and is an excellent preventive measure against heart disease and atherosclerosis.
• Bran bread is one of the most healthy. It absorbs toxins and allergens and helps strengthen the immune system. The bread is rich in fiber, minerals, and proteins.
• Poppy seed bread: has a beneficial "soothing" effect on the respiratory and urinary tracts.
• Sesame bread: rich in calcium, phosphorus, and vitamin E.
• Flax bread contains a high percentage of iodine and vitamin E and regulates bowel function.
• Bread with sunflower seeds contains a lot of fiber, protein, and mineral substances, especially potassium and iron. The bread is rich in phosphorus and valuable vitamin E.
• Rye bread is rich in potassium. It is recommended for hypertension, atherosclerosis, and vascular diseases in general. It is digested more slowly than white bread and contains more beneficial substances.
• Corn bread: rich in cereal fats, does not contain gluten, which makes it easy on the digestive system.

5.2.2. Requirements for bread quality

Bread quality is determined by organoleptic and physicochemical indicators in accordance with the requirements of standards. Organoleptic indicators include appearance, condition of the crust and crumb, taste, and smell.

The shape of the product must be correct, corresponding to the given type of product. Hearth bread has an oval, elongated, or round shape, without overhanging edges; tin bread has a slightly convex crust, without overhanging edges. The surface is smooth, without large cracks, tears, blisters, and contaminants. Crust color: wheat bread - from golden yellow to light, rye bread - from brown to dark brown, crust thickness - no more than 3-4 mm. The crust is without tears and cracks.

The crumb should be well-baked, not sticky, not moist to the touch, elastic, and free of lumps or traces of unmixed ingredients. The porosity should be uniform and well-developed. The taste and aroma must correspond to the type of product, without any off-flavors or foreign odors.

Physicochemical indicators include moisture content, acidity, and porosity.

Increased moisture content reduces caloric value and impairs the quality of the bread. It becomes heavier and less digestible. Such bread is more susceptible to mold, diseases, and deforms easily. Low moisture content causes the bread to become dry, go stale quickly, and degrades its flavor.

Acidity is expressed in degrees. During the dough fermentation process, lactic acid accumulates. Normal acidity improves the flavor of bread; a deficiency makes the bread bland, while an excess makes it sour.

Porosity of bread is the volume of pores expressed as a percentage of the total volume of the bread crumb. Digestibility is linked to this indicator. Bread with uniform fine porosity that is well-leavened is better permeated by digestive juices and therefore more fully absorbed.

Causes of bread defects are linked to the quality of the primary and auxiliary raw materials, deviations in dosage and the technological process, or careless handling of the bread after baking.

Defects and diseases of bread: causes and preventive measures

The quality of finished bread depends directly on the properties of the flour, compliance with the recipe, and baking parameters. Violation of technological regimes leads to the appearance of external defects and crumb faults. Irregular shape, tears, and cracks in the crust most often indicate insufficient proofing of the dough, excessively high temperatures in the oven, or a lack of steam. The use of low-quality raw materials or under-fermented dough results in a pale crust and charred blisters that burst quickly.

Specialists identify the following main crumb defects:

• Unmixed areas — sections containing dry flour, salt, or chunks of poorly soaked returned bread.
• Crust separation — the result of placing under-fermented dough into an overheated oven, where accumulated gases and water vapor detach the top crust.
• Heavy/dense layer (zakal) — a non-porous moist layer near the bottom crust, occurring due to a sharp temperature drop between the dough and the hearth, excess water, underbaking, or stacking hot bread too densely.
• Crumbliness — a consequence of insufficient water during mixing or prolonged storage of the products.
• Uneven porosity — occurs if the dough is under-fermented or poorly kneaded during fermentation.
• Underbaking — the crumb is sticky, and the depression from finger pressure recovers slowly due to excess water, weak flour, or short baking time.

In addition to technological defects, bread is susceptible to specific diseases. The most dangerous is the "potato disease," caused by the bacteria Bacillus mesentericus, whose spores survive baking. The disease affects wheat bread in the summer if the bakery's sanitary conditions are poor, turning the crumb into a dark, ropy mass with a sharp odor. Chalk mold is caused by yeast fungi and manifests as white powdery spots. Molding occurs when the storage rules for finished products are violated.

Rules for storing finished products and shock freezing

To preserve their commercial appearance, bread is transported in special trays on equipped vehicles. In warehouses, it is stacked loosely in one or two rows on racks, shelves, or mobile trolleys. The storage facility must be clean, dry, and well-ventilated.

• Storage temperature — 20–25 °C
• Minimum temperature threshold — 6 °C
• Air humidity — no more than 75%
• Shelf height from the floor — 0.5 m

During storage, bread inevitably dries out and stales due to the firming of protein and starch structures. To slow this process, malt, molasses, or scalded flour (zavarka) are added to the recipe. Stale crumb can be temporarily softened by heating, as the starch reabsorbs moisture. Maintaining the storage temperature at 60 °C almost stops staling, but accelerates drying out due to the evaporation of free moisture.

The technology for freezing finished bread includes the following sequential stages:

1. Cooling freshly baked bread for 1–2 hours.
2. Freezing at a temperature from minus 24 to minus 32 °C for 12.5 hours.
3. Storage of finished products at a temperature of minus 15 °C for 6–8 weeks.
4. Heating the bread to plus 50 °C immediately before consumption.

Basic methods of vegetable preservation

Physical, chemical, and biochemical methods of preservation help maintain the quality of harvested vegetables and prevent their spoilage. Each of these methods is aimed at stopping the development of undesirable microflora and inhibiting biochemical processes in plant tissues. The choice of a specific technology depends on the intended purpose of the product and the available processing facilities.

Physical methods of preservation are based on temperature exposure and moisture removal. During freezing and drying, microorganisms are deprived of the conditions necessary for life, while thermal sterilization completely destroys their cellular structures. Ultrasonic treatment is also used, which causes protein coagulation and the breakdown of pathogen cells.

Chemical and biochemical methods alter the acidity of the environment, making it unsuitable for putrefactive bacteria. In pickling, acidity is increased artificially by adding acetic acid to the product. In biochemical processes, the preservative is lactic acid, which is produced by bacteria during the fermentation of the vegetables' own sugars.

• Freezing temperature — below -10 °C
• Acetic acid concentration — 0.5–2.0 %
• Sugar content of cabbage for fermentation — not less than 4–5 %
• Fermentation temperature of vegetables — 18–20 °C
• Storage temperature of products — 0–4 °C

Technology of salting and fermenting vegetables

Salting and fermenting are classic biochemical methods of preservation based on lactic acid fermentation. The difference lies mainly in the type of raw material processed: it is customary to salt cucumbers and tomatoes, and ferment cabbage. In both processes, sugar is converted into lactic acid under the action of lactic acid bacteria.

Common salt is used to extract cell sap, which causes plasmolysis of plant cells. Salt is added in an amount of 2–3 % directly to the shredded raw material or applied in the form of a 4–8% brine when salting whole vegetables. In this case, aromatic additives must be added to the brine: dill, caraway, horseradish, and garlic.

When producing sauerkraut, it is important to select cultivars with large, dense heads and a small inner core. The best products are obtained from high-sugar raw materials with white, non-coarse leaves. The finished cabbage is produced in shredded form with strips up to 5 mm wide, chopped with a particle size up to 12 mm, or as whole heads.

Fermentation is carried out in wooden vats of a conical shape with a height and average diameter of 3 meters or more. The optimal temperature regime for bacterial activity is 18–20 °C, with strict adherence to sanitary conditions. Salted and fermented products are stored at a temperature of 0–4 °C, while salted cucumbers in ordinary storage facilities reach readiness after 30 days.

The recipe for preparing sauerkraut is calculated strictly according to the norms of raw material consumption per one ton of finished product. In addition to the main ingredients, flavoring additives and spices are added to the vats according to the recipe. The composition and ratio of components are presented in the table below.

Technology of cabbage fermentation and preparation of raw materials

The quality of the finished sauerkraut directly depends on the precision of observing technological parameters during the preparation of raw materials. Violation of the cutting sizes or packing density prevents the proper release of juice and interferes with the creation of an anaerobic environment, which can spoil the entire batch of the product. To start healthy lactic acid fermentation, it is necessary to strictly adhere to the recipe and temperature regime.

• Shredding productivity — 8–10 t/h
• Cabbage cutting width — up to 5 mm
• Cabbage cutting thickness — up to 3 mm
• Carrot cutting thickness — 3 mm
• Salt consumption — 1.8–2% of the cabbage mass
• Caraway seed consumption — 0.5 kg/t of cabbage

1. Preparation and shredding. Manually clean the cabbage heads and shred them using shredding machines (particle length is arbitrary). Simultaneously, wash and clean the carrots in washing machines and root peelers with manual finishing, then shred them using root cutters or shredding machines to a thickness of 3 mm with a length and diameter of 5 to 40 mm (the proportion of carrots is 3–4% of the cabbage mass).
2. Mixing with spices. Thoroughly wash the spices and sift the salt. To the prepared cabbage, add 3% carrots, 1.8–2% salt, and caraway seeds, previously mixed with salt.
3. Packing and tamping. Cover the bottom of the vat with clean cabbage leaves. Fill the container continuously and in layers, mixing the mass with wooden poles. Pack the cabbage tightly and tamp it thoroughly to accelerate juice release and create anaerobic conditions.
4. Covering and setting the weight. Cover the cabbage with leaves, cheesecloth, or cloth, then install the pressing disc. Ensure that the released juice reaches half the thickness of the pressing disc.

The onset of lactic acid fermentation is determined visually: the brine begins to turn cloudy, gas bubbles appear on the surface, and then a snow-white foam forms. The speed of the process and the quality of the finished product depend on the temperature conditions in the room.