Processes in bread during baking

[PROCESSES OCCURRING IN BREAD DURING ITS BAKING]

PROCESSES OCCURRING IN BREAD DURING ITS BAKING

Prof. A. Ya. Auermann. 1942 year

1.1 Warming up the dough-bread

Bread products are baked in the baking chamber of a baking oven at an air-vapor temperature of 200-280 ° C. Baking 1 kg of bread requires about 293-544 kJ. This heat is mainly spent on evaporation of moisture from the dough piece and on heating it to a temperature of 96-97 ° C in the center, at which the dough turns into bread. A large proportion of heat (80-85%) is transferred to the dough-bread by radiation from the hot walls and arches of the baking chamber. The rest of the heat is transferred by conduction from the hot hearth and by convection from the moving currents of the steam-air mixture in the baking chamber.
The dough pieces are heated gradually, starting from the surface, therefore, the processes typical for baking do not take place simultaneously in the entire mass of bread, but in layers - first in the outer layers, then in the inner layers. The speed of heating the dough-bread as a whole, and, consequently, the duration of baking depends on a number of factors. As the temperature in the baking chamber rises, the workpieces are heated faster and the baking time is shortened. Dough with high moisture content and porosity heats up faster than strong and dense dough.
Dough pieces of significant thickness and weight, all other things being equal, heat up longer. Shaped bread is baked more slowly than hearth bread. The tight fit of the dough pieces on the bottom of the oven slows down the baking of the products.

1.2 Formation of a hard bread crust

This process occurs as a result of dehydration of the outer layers of the dough piece. It is important to note that the hard crust stops the growth of the dough and bread volume, and therefore the crust should not form immediately, but 6-8 minutes after the start of baking, when the maximum volume of the piece has already been reached.
For this purpose, steam is supplied to the first zone of the baking chamber, the condensation of which on the surface of the workpieces delays dehydration of the top layer and the formation of a crust. However, after a few minutes, the top layer, warming up to a temperature of 100 ° C, begins to quickly lose moisture and at a temperature of 110-112 ° C turns into a thin crust, which then gradually thickens.
When the crust is dehydrated, part of the moisture (about 50%) evaporates into the environment, and part passes into the crumb, since when various materials are heated, moisture always passes from the more heated areas (crust) to less heated areas (crumb). The moisture content of the crumb as a result of the movement of moisture from the crust increases by 1.5-2.5%. By the end of baking, the moisture content of the crust is only 5–7%, which means that the crust is practically dehydrated.
The temperature of the crust reaches 160-180 ° C by the end of baking. Above this temperature, the crust does not heat up, since the heat supplied to it is spent on moisture evaporation, overheating of the resulting steam, and also on crumb formation.
The following processes take place in the surface layer of the workpiece and in the crust: gelatinization and dextrinization of starch, denaturation of proteins, formation of aromatic and dark-colored substances and removal of moisture. In the first minutes of baking, as a result of steam condensation, starch on the surface of the workpiece is gelatinized, partially passing into soluble starch and dextrins. A liquid mass of soluble starch and dextrins fills the pores located on the surface of the workpiece, smoothes out minor irregularities and, after dehydration, gives the crust a shine and gloss.
Denaturation of protein substances on the surface of the product occurs at a temperature of 70-90 ° C. Protein coagulation, along with dehydration, contributes to the formation of a dense, inelastic crust. Until a certain time, the color of the crust of bread was associated with the amount of residual, unfermented sugars in the dough at the time of baking. For a normal color of the crust, the dough before baking must contain at least 2-3% unfermented sugars. The higher the sugar and gas forming ability of the dough, the more intense the color of the bread crust.
Previously, it was believed that the products that determine the color of the crust of bread are brown-colored products of caramelization or primary hydration of residual dough sugars not fermented at the time of baking. Caramelization and dehydration of sugars in the crust was explained by its high temperature. Some researchers believe that colored products of thermal dextrinization of starch and thermal changes in protein substances of the crust play a role in the color of the crust.
Based on a number of studies, it can be assumed that the intensity of the color of the bread crust is mainly due to the formation in it of dark-colored products of the redox interaction of residual, unfermented reducing dough sugars and protein proteolysis products contained in the dough, that is, melanoidins. In addition, the color of the crust depends on the baking time and the temperature in the baking chamber.

1.3 Internal movement of moisture in bread

When baking, the moisture content of the inside of the bread changes. An increase in the moisture content of the outer layers of a baked product in the initial phase of baking with a strong humidification of the gaseous environment of the baking chamber and a subsequent decrease in the moisture content of the surface layer to equilibrium moisture, which occurs as this layer turns into a crust, were noted above. In this case, not all the moisture evaporating in the baked bread in the evaporation zone passes in the form of steam through the pores of the crust into the baking chamber.
The crust is much more compact and much less porous than the crumb. The pore size in the crust, especially in its surface layer, is many times smaller than the pore size in the adjacent crumb layers. As a result, the crust of bread is a layer that offers great resistance to steam passing through it from the evaporation zone into the baking chamber. Part of the steam generated in the evaporation zone, especially above the bottom crust of the bread, can rush out of it through the pores and crumb holes into the crumb layers adjacent to the evaporation zone from the inside. Reaching the layers located closer to the center and less heated, water vapor condenses, thereby increasing the moisture content of the layer in which the condensation has occurred.
This crumb layer, which is, as it were, a zone of internal condensation of water vapor in baked bread, corresponds to the configuration of isothermal surfaces in bread. For the internal movement of moisture in a wet material, there must be a difference in transfer potential. In baked dough bread, there can be two main reasons for moisture transfer: a) the difference in moisture concentration in different parts of the product and b) the difference in temperature in individual parts of the dough bread.
The difference in moisture concentration is an incentive to move moisture in the material from areas with a higher moisture concentration to areas with a lower moisture concentration. Such movement is conventionally called concentration (concentration diffusion or concentration moisture conductivity).
Temperature differences in individual areas of wet material also cause moisture to move from areas of the material with a higher temperature to areas with a lower temperature. This movement of moisture is conventionally called thermal.
In baked bread, both a large difference in the moisture content of the crust and crumb and a significant temperature difference between the outer and central layers of the bread during the first baking period are observed.As the works of domestic researchers have shown, when baking bread, the stimulating effect of the temperature difference in the outer and inner layers prevails, and therefore the moisture in the crumb during the baking process moves from the surface to the center.
Experiments show that the moisture content of the crumb of bread in the baking process increases by about 2% compared to the original moisture content of the dough. Moisture increases most rapidly in the outer layers of the crumb during the initial period of the baking process, which is explained by the large role of thermal and moisture conductivity in this period of baking due to the significant temperature gradient in the crumb.
From a number of works it follows that during baking, the moisture content of the surface layer of a piece of dough quickly drops and very quickly reaches the level of equilibrium moisture content, due to the temperature and relative humidity of the steam-air mixture. Deeper layers and later turning into a crust layer more slowly reach the same equilibrium moisture content.

1.4 Crumbling

When baking inside the dough piece, fermentative microflora is suppressed, enzyme activity changes, starch gelatinization and thermal denaturation of proteins occur, humidity and temperature of the inner layers of the dough-bread change. The vital activity of yeast and bacteria in the first minutes of baking increases, as a result of which alcohol and lactic acid fermentation is activated. At 55-60 ° C, yeast and non-thermophilic lactic acid bacteria die off.
As a result of the activation of yeast and bacteria at the beginning of baking, the content of alcohol, carbon monoxide and acids slightly increases, which has a positive effect on the volume and quality of the bread. The activity of enzymes in each layer of the baked product first increases and reaches a maximum, and then drops to zero, since enzymes, being protein substances, coagulate when heated and lose the properties of catalysts. The activity of a-amylase can have a significant effect on the quality of the product, since this enzyme is relatively resistant to heat.
In rye dough, which is highly acidic, a-amylase is destroyed at a temperature of 70 ° C, and in wheat dough only at temperatures above 80 ° C. If the dough contains a lot of a-amylase, then it will convert a significant part of the starch into dextrins, which will degrade the quality of the crumb. Proteolytic enzymes in bread doughs are inactivated at 85 ° C.
A change in the state of starch, together with changes in protein substances, is the main process that turns the dough into bread crumb; they happen almost simultaneously. Starch grains gelatinize at temperatures of 55-60 ° C and above. Cracks form in the starch grains, into which moisture penetrates, which is why they increase significantly. During gelatinization, starch absorbs both the free moisture of the dough and the moisture released by the curdled proteins. Starch gelatinization occurs when there is a lack of moisture (for complete starch gelatinization, the dough must have 2-3 times more water), there is no free moisture left, so the crumb of the bread becomes dry and non-sticky to the touch.
The moisture content of the crumb of hot bread (in general) rises by 1.5-2% compared to the moisture content of the dough due to moisture transferred from the upper layer of the workpiece. Due to the lack of moisture, starch gelatinization is slow and ends only when the central layer of the dough is heated to a temperature of 96-98 ° C. The temperature of the center of the crumb does not rise above this value, since the crumb contains a lot of moisture, and the heat supplied to it will not be spent on heating the mass, but on its evaporation.
When baking rye bread, not only gelatinization occurs, but also acid hydrolysis of a certain amount of starch, which increases the content of dextrins and sugars in dough bread. Moderate hydrolysis of starch improves the quality of the bread.
The change in the state of protein substances begins at a temperature of 50-70 ° C and ends at a temperature of about 90 ° C.Protein substances in the baking process undergo thermal denaturation (coagulation). At the same time, they become denser and release moisture absorbed by them during the formation of the dough. Curdled proteins fix (fix) the porous structure of the crumb and the shape of the product. A protein framework is formed in the product, into which grains of swollen starch are interspersed. After thermal denaturation of proteins in the outer layers of the product, the increase in the volume of the workpiece stops.
The final moisture content of the inner surface of the layer adjacent to the crumb can be taken approximately equal to the initial moisture content of the dough (W0) plus an increase due to the internal movement of moisture (W0 + DW), while the outer surface of this layer adjacent to the crust has a moisture content equal to equilibrium humidity. Based on this, on the graph for this layer, the value of the final moisture content is taken, the average between the values ​​(W0 + DW) and W0Р.
The moisture content of the individual layers of the crumb also increases during the baking process, and the increase in moisture occurs first in the outer layers of the crumb, then captures more and more deeply located layers. As a result of the thermal movement of moisture (thermal moisture conductivity), the moisture content of the outer layers of the crumb, closer to the evaporation zone, even begins to decrease somewhat against the maximum reached. However, the final moisture content of these layers is still higher than the original moisture content of the dough when baking starts. The moisture in the center of the crumb builds up the slowest, and its final moisture may be slightly less than the final moisture in the layers adjacent to the center of the crumb.

1.5 Vital activity of the fermenting microflora of the dough during the baking process

The vital activity of the fermenting microflora of the dough (yeast cells and acid-forming bacteria) changes as a piece of dough-bread heats up during the baking process.
When the dough is heated to about 35 ° C, yeast cells accelerate the fermentation and gas formation process they cause to a maximum. Up to approx. 40 ° C, the yeast activity in the baked dough is still very intense. When the dough is heated to a temperature above 45 ° C, gas formation caused by the yeast is sharply reduced.
Previously, it was believed that at a dough temperature of about 50 ° C, yeast dies off.
The vital activity of the acid-forming microflora of the dough, depending on the temperature optimum (which is about 35 ° C for non-thermophilic bacteria, and about 48-54 ° C for thermophilic bacteria), is first forced as the dough warms up, and then, after reaching the temperature above the optimum, it stops.
It was believed that when the dough is heated to 60 ° C, the acid-forming flora of the dough completely dies off. However, the work carried out by a number of researchers suggests that in the crumb of ordinary rye bread made from wallpaper flour, although in a weakened, but viable state, individual cells of both yeast and acid-forming bacteria are preserved.
From the fact that a small part of the viable fermentative microflora of the dough is retained in the crumb of bread during baking, it does not in any way follow that fermentative microorganisms can, under all conditions, withstand the temperature of 93-95 ° C, which is reached in the center of the bread during baking.
It was also shown that boiling the crumb of bread, pounded in excess water, killed all types of fermentative microorganisms.
Obviously, the preservation of a part of the fermenting microflora of the dough in the crumb of bread in a viable state can be explained by both a very small amount of free water and a very short-term rise in the temperature of its central part above 90 ° C.
From the above data, it follows that the temperature optima for the fermenting microflora of the dough, determined under the conditions of the environment, in consistency different from the dough, may be underestimated in comparison with the optima acting under the conditions of the baked dough-bread.
Obviously, it should be considered that when the dough is heated to about 60 ° C, the vital activity of yeast and non-thermophilic acid-forming bacteria of the dough practically stops. Thermophilic lactic acid bacteria such as Delbrück bacteria can be fermentatively active even at higher temperatures (75-80 ° C).
The changes described above in the vital activity of the fermenting microflora of the baked piece of dough occur gradually, as it warms up, spreading from the surface layers to the center.

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[1.6 Biochemical processes occurring in dough-bread during baking]

1.6 Biochemical processes occurring in dough-bread during baking

In the dough, and then in the crumb formed from it, the following biochemical processes and changes are observed.
Fermentation, caused by yeast and acid-forming bacteria, lasts when baking dough until the temperature of the individual layers of the crumb dough reaches a level at which the vital activity of these fermenting microorganisms ceases.
Therefore, in the initial period of baking, a small amount of alcohol, carbon dioxide, lactic and acetic acid and other fermentation products continue to form in the crumb dough.
When baking dough-bread, the starch contained in it, which has passed the first stages of the gelatinization process, is partially hydrolyzed. As a result, the starch content of the dough bread decreases to a certain extent during baking.
As long as the dough amylases are not yet inactivated due to the increase in the dough temperature, they cause starch hydrolysis. In the process of baking bread, the attackability of starch by amylases increases. This is explained by the fact that starch, even in the initial stages of its gelatinization, is much more easily hydrolyzed by b-amylase.
a-amylase is inactivated during baking at a significantly higher temperature than b-amylase. In the baking time interval, when b-amylase is already inactivated, and a-amylase is still active, a significant amount of dextrins accumulates in the crumb, which makes the crumb sticky and damp to the touch.
This is facilitated by the fact that the action of a-amylase on starch reduces its water-holding capacity. Therefore, when baking bread from wheat flour, ground from sprouted grain, the acidity of the dough should be increased, which reduces the temperature of inactivation of a-amylase. Rye flour, even from non-sprouted grains, contains a certain amount of active a-amylase, therefore rye dough is cooked at a higher acidity.
If you bake bread from rye dough with an acidity of about 4 °, then a-amylase is also able to retain a certain activity until the end of baking, that is, up to a temperature above 96 ° C. Therefore, the action of amylolytic enzymes in dough bread during baking significantly affects the quality of the bread. The sugars formed in dough bread during baking as a result of starch amylolysis are partially consumed for fermentation in the first part of the baking period.
In the baking process, there is also a partial hydrolysis of high molecular weight pentosans in rye dough, which are converted into water-soluble, relatively low molecular weight pentosans. Thus, in the process of baking bread, the amount of water-soluble carbohydrates increases sharply, mainly causing an increase in the total content of water-soluble substances. Protein-proteinase complex of bread dough during baking also undergoes a number of changes associated with its heating.
In the baked dough bread, proteolysis occurs to a certain degree of its heating. In a wheat flour dough with a humidity of 48% and a pH at the end of fermentation equal to 5.85, the optimum temperature for the accumulation of water-soluble nitrogen in the dough with a heating time of 30 minutes is about 60 ° C, and with 15 minutes of heating - about 70 ° C. An increase in the moisture content of the water-flour environment to 70% reduces this optimum to 50 ° C.
It should also be noted that the temperature of inactivation of enzymes in dough-bread during baking depends on the heating rate of the baked product.The faster the bread dough, the higher the temperature at which enzymes are inactivated. From 70 ° C, the proteins of the heated wheat dough undergo thermal denaturation.
The biochemical processes that occur when baking bread in its crust also significantly affect the quality of the bread. The crust contains significantly more water-soluble substances and dextrins. However, enzymatic hydrolysis does not play a leading role in this. The crust and the surface layers of the dough, from which it is formed, warm up very quickly, and therefore the enzymes are inactivated very soon. The accumulation of dextrins and, in general, water-soluble substances in the crust of bread during baking is largely explained by the thermal change in starch and, in particular, its thermal dextrinization (the surface temperature of the crust reaches 180 ° C, and the middle of the crust reaches 130 ° C).

1.7 Colloidal processes in dough-bread during baking

The colloidal processes occurring when the bread is heated are very significant, since it is they that determine the transition of the dough into the crumb of the bread.
A change in the temperature of the dough dramatically affects the course of colloidal processes occurring in it. Dough gluten has a maximum swelling capacity at about 30 ° C. A further increase in temperature leads to a decrease in its ability to swell. At about 60-70 ° C, the proteins of the dough (its gluten) denature and coagulate, releasing the water absorbed during swelling.
The starch of flour swells more and more vigorously as the temperature rises. Swelling increases especially rapidly at 40-60 ° C. In the same temperature range, starch gelatinization begins, accompanied by its swelling. However, the gelatinization process is very complicated. According to V.I. Nazarov's works, gelatinization cannot be identified with swelling. If the starch gelatinization was limited to swelling only, then the thermal effect of the gelatinization process would be positive. However, the gelatinization of starch occurs with a pronounced endothermic effect, which, according to Nazarov, is explained by the expenditure of heat for the destruction of the internal micellar structure of the starch grain and the separation of larger micellar aggregates into individual micelles or smaller groups of micelles.
The consequence of this is an increase in osmotic pressure inside the starch grain, and the intense inflow of water caused by this pressure into the grain leads to rupture of the starch grain shell and its complete destruction. The starch grains remain in the bread in a semi-gelatinized state, partially retaining their crystalline structure.
In the temperature range of 50-70 ° C, therefore, the processes of coagulation (thermal coagulation) of proteins and gelatinization of starch occur simultaneously. The bulk of the water absorbed by the proteins of the dough when they swell goes to gelatinous starch.
No less important is the fact that the processes of starch gelatinization and protein coagulation cause the transition of the dough during baking to the state of bread crumb, while dramatically changing the physical properties of the dough and, as it were, fixing the porous structure of the dough, which it had at that time.
The transition of the dough into the crumb does not occur simultaneously throughout its entire mass, but begins from the surface layers and, as it warms up, spreads towards the center of the piece of bread. If in the middle of baking, you take the bread out of the oven and cut it, you can see that in the central part of the bread there is still an unchanged dough surrounded by a layer of crumb that has already formed. The border between bread and crumb. The border between crumb and dough in wheat bread will be an isothermal surface, the temperature of which will be about 69 ° C.

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[2 Increase the volume of baked goods]

2 Increase the volume of baked goods

The volume of the baked product is 10-30% more than the volume of the dough piece before planting it in the oven.The increase in product volume occurs mainly in the first minutes of baking as a result of residual alcoholic fermentation, the transition of alcohol into a vapor state at a temperature of 79 ° C, as well as thermal expansion of vapors and gases in the dough piece. An increase in the volume of dough-bread improves the appearance, provides the necessary porosity and increases the digestibility of the product.
The degree of increase in the volume of a baked piece of bread depends on the condition of the dough, the method of planting the blanks on the oven, the baking mode and other factors. A sufficiently high hearth temperature in the first zone of the oven (about 200 ° C) causes intensive formation of vapors and gases in the lower layers of the dough. Couples, rushing upward, increase the volume of the workpiece. When planting a workpiece on a cold hearth, the products become vague and their volume decreases. Good moisture in the first zone delays the formation of a hard crust and promotes the growth of bread volume. Planting dough pieces on the underside of the oven with overturning compresses the dough, removes some of the gases from it and somewhat reduces the volume of the product.

3 Influence of the baking regime on the quality of the bread product

The baking mode is understood as its duration, as well as the temperature and humidity of the environment in different zones of the baking chamber. All products are baked in an alternating mode, as a result, there should be several zones in the baking chamber with different humidity and ambient temperatures. For most products (hearth bread, baked goods, etc.), a mode is recommended in which the dough pieces successively pass through the zones of humidification, high and low temperatures.
In the humidification zone, which is sometimes outside the oven, a comparatively high environmental humidity (64-80%) and a low temperature (120-160 ° C) should be maintained compared to other zones. The higher temperature delays the condensation of steam on the surface of the dough pieces. Steam condensation accelerates the heating of the dough-bread, increases the volume of the product, improves the taste, aroma and condition of its surface, and reduces the bale. Heating of the workpiece is accelerated due to the fact that the latent heat of vaporization (22736.6 kJ) is released during steam condensation.
The greater increase in the volume of the dough piece is explained by the fact that humidification delays the formation of a hard crust, which prevents the expansion of vapors and gases. The surface condition is improved by the formation of a layer of liquid starch paste on the wetted surface of the workpiece. The paste smooths out irregularities, closes pores, and further provides a smooth shiny crust that retains aromatic substances well. Insufficient moisture causes defects in hearth products.
The steam consumption for baking 1 ton of bakery products is theoretically 40 kg, and practically, as a result of a significant steam loss in baking ovens, it ranges from 200-300 kg. For more moisture, the dough pieces are often sprayed with water before planting in the oven. Under the oven in the planting area of ​​the hearth products should be well heated (temperature 180-200 ° C). The dough pieces remain in the moistening zone for 2-5 minutes. During this period, the workpieces slightly increase in volume and are heated to a temperature of 35-40 ° C in the center and 70-80 ° C on the surface.
In the high temperature zone (270-290 ° C), the medium of the baking chamber is not humidified. The previously moistened dough piece, getting into this zone, first intensively increases in volume as a result of the transition of alcohol to steam and thermal expansion of vapors and gases. And then the achieved volume of the workpiece is quickly fixed (fixed) as a result of the formation of a hard crust. The surface of the dough piece in this zone is heated to a temperature of 100-110 ° C, and the central layers of the crumb - to a temperature of 50-60 ° C. At this temperature, starch gelatinization and protein coagulation begin, therefore, in the high temperature zone, the initial formation of crumb and crust occurs.
This part of baking takes 15-22% of the total baking time.In the low temperature zone (220-180 ° C), the bulk of the baking takes place, in which the processes of crust and crumb formation continue and end. Lowering the temperature in this zone reduces the baking, but at the same time does not slow down the baking process, since the temperature of the environment of the baking chamber, from which the crumb receives heat, remains above the temperature of the crust. Regardless of the temperature in the chamber, the crust does not heat up above 160-180 ° C during baking.
The baking mode of each type of bread product has its own characteristics, it is influenced by the physical properties of the dough, the degree of proofing of the workpieces and other factors. So, blanks made from weak dough (or those that have received a long proofing) are baked at a higher temperature to prevent the products from blurring.
If the products are baked from youthful dough, then the temperature of the environment of the baking chamber is somewhat reduced, and the duration of baking is correspondingly increased in order that the necessary ripening and loosening processes continue in the first minutes of baking. Products of smaller mass and thickness are heated and baked faster than products of larger weight and thickness.
If large breads are baked at a high temperature, the crust may burn while the crumb is not yet baked. Products with a high sugar content are baked at a lower temperature and longer than products with a low sugar content, otherwise the crust of the bread will be too dark.
The baking mode in baking ovens is controlled in accordance with the technological requirements. From a technological point of view, it is necessary that the design of the ovens provides an optimal baking mode for a wide range of products. It is important that the natural ventilation of the baking chamber is kept to a minimum in order to reduce the loss of heat, steam, aromas and baking. The thermal inertia of the furnace should be negligible, which is necessary to accelerate the heating of a cold furnace after a long break in operation, as well as to rapidly change the temperature.

4 Upek

Upek - a decrease in the mass of dough during baking, which is determined by the difference between the mass of the dough piece before planting in the oven and the finished hot product that came out of the oven, expressed as a percentage of the weight of the piece.
The main reason for baking is moisture evaporation during crust formation. To an insignificant extent (by 5-8%) the bale is due to the removal of alcohol, carbon monoxide, volatile acids and other volatile substances from the dough piece. Studies have shown that 80% of alcohol, 20% of volatile acids and almost all of the carbon dioxide are removed from dough bread during baking. The amount of baking for different types of bread products is in the range of 6-12%. First of all, the size of the bale depends on the shape and weight of the dough piece, as well as on the method of baking the product (in molds or on the bottom of the oven).
The less the weight of the product, the more its packing (all other things being equal), since the packing occurs due to dehydration of the crusts, and the specific content of crusts in small-piece items is higher than in large ones. Shaped products have a smaller bale because the side and bottom crusts of the tin bread are thin and moist. All crusts of hearth bread, especially the bottom one, are relatively thick, with low moisture content.
The bale of the same product in different ovens may differ depending on the baking mode and oven design. A product baked under optimal conditions has a smaller bale in the humidified zone than a product baked with insufficient moisture. Spraying the surface of the products with water before leaving the oven reduces the bale by 0.5%. In addition, this operation contributes to the formation of gloss on the surface.
A rational baking temperature regime contributes to a thin crust and a decrease in baking. The bale must be uniform across the width of the hearth of the oven, otherwise the products will have different weights and the thickness of the crusts. At bakeries, the optimal amount of baking is set for each type of product in relation to local conditions.Excessive decrease in bale deteriorates the condition of the crusts, they become very thin and pale. An increase in bale leads to thickening of the crusts, a decrease in product yield. Upek is the largest technological cost in the baking process.

5 Determination of the readiness of baked bread

An accurate determination of the readiness of the baked product is essential. Unbaked bread has a sticky crumb crumb, and sometimes external defects. Excessive baking time increases the bale, reduces the oven productivity, and causes excessive fuel consumption. An objective indicator of the readiness of products is the temperature of the center of the crumb, which should be 96-97 ° C at the end of baking. In production, the readiness of products is determined, in particular, organoleptically according to the following characteristics:
- peel color (color should be light brown);
- the state of the crumb (the crumb of the finished bread should be relatively dry and elastic). Determining the state of the crumb, hot bread is broken, avoiding creasing. The state of the crumb is the main sign of bread readiness;
- relative mass. The mass of the baked product is less than the mass of the unfinished product due to the difference in packing.

[Dough fermentation and maturation. (alcoholic and lactic acid fermentation)]

Dough fermentation and maturation. (alcoholic and lactic acid fermentation)

During fermentation, the dough and other semi-finished products are not only loosened, but also ripen, that is, they reach an optimal state for further processing.
The ripened dough has certain rheological properties, sufficient gas-forming and gas-holding capacity.

The dough accumulates a certain amount of water-soluble substances (amino acids, sugars, etc.), aromatic and flavoring substances (alcohols, acids, aldehydes).
The dough becomes loosened, significantly increases in volume. Ripening and loosening of the dough occurs not only during its fermentation from kneading to cutting, but also during cutting, proofing and in the first minutes of baking, since, due to temperature conditions, fermentation continues at these stages.

Dough maturation is based on microbiological, colloidal and biochemical processes.

The main microbiological processes are alcoholic and lactic acid fermentation.

ALCOHOL FERMENTATION

Yeast fermentation is a complex process involving multiple enzymes. The overall equation of alcoholic fermentation does not give an idea of ​​its complexity.

Fermentation starts already when the dough is kneaded.
In the first 1-1.5 hours, yeast ferments its own flour sugars, then, if sucrose is not added to the dough, yeast begins to ferment maltose, which is formed during the hydrolysis of starch under the action of β-amylase. Fermentation of maltose is possible only after its hydrolysis by the yeast enzyme - maltose, since there is no maltose in the flour and raw materials.

By the nature of production, yeast has a low maltose activity, since it is grown in a maltose-free environment. The restructuring of the enzyme apparatus of the yeast cell for the formation of maltose takes some time. In view of this, after fermenting the flour's own sugars, the intensity of gas formation in the dough decreases, and then (when maltose begins to ferment) it increases again.
If sucrose is added to the dough, then it turns into glucose and fructose within a few minutes after kneading under the action of yeast invertase.

The intensity of alcoholic fermentation depends on the amount of fermenting activity of the yeast, on the recipe, temperature and humidity of the dough, on the intensity of the dough kneading, on the improvers added during the kneading and the content in the environment of substances necessary for the life of the yeast.

Gas formation in the dough accelerates and reaches its maximum faster with an increase in the amount of yeast or an increase in its activity, with a sufficient content of fermentable sugars, amino acids, phosphate salts

The increased content of salt, sugar, fat inhibits the process of gas formation.

Fermentation is accelerated by adding amylolytic enzyme preparations, whey.

The temperature of the dough especially affects the process of alcoholic fermentation.With an increase in the temperature of the dough from 26 to 35C, the intensity of gas formation doubles.

LACTIC FERMENTATION

Fermentation in semi-finished products is caused by various types of lactic acid bacteria. In relation to temperature, lactic acid bacteria are divided into thermophilic (optimal temperature 40-60C) and mesophilic (non-thermophilic) for which the optimal temperature is 30-37C. Mesophilic bacteria are the most active in semi-finished products of bakery production.

By the nature of the fermentation of sugars, lactic acid bacteria are divided into homofermentative and heteroenzymatic.
Differences in enzyme systems determine the ability of homoenzymatic bacteria to ferment sugar with the formation of lactic acid, and heteroenzymatic bacteria - several substances.
The products of homofermentative fermentation contain 95% lactic acid, and heteroenzymatic fermentation - 60-70%.
Lactic acid bacteria ferment hexoses, disaccharides and some types of bacteria - pentoses.

Lactic acid fermentation is especially intense in the rye flour dough.

Lactic acid bacteria get into wheat dough accidentally with flour, yeast, milk whey.

Rye dough is prepared with sourdoughs, in which special conditions are created for the reproduction of lactic acid bacteria.

It is noted that lactic acid fermentation proceeds more intensively in semi-finished products with a thick consistency.

During the fermentation of semi-finished products, the acidity increases, and the pH decreases.

Acidity is the most objective indicator of the readiness of semi-finished products during fermentation.

The composition and amount of dough acids affect the state of protein substances, enzyme activity, fermentation microflora, the taste and aroma of bread.
The intensity of lactic acid fermentation is influenced by the temperature and humidity of semi-finished products, the dosage of sourdough or other products containing lactic acid bacteria, the composition of the acid-forming microflora, and the intensity of dough kneading.

Good evening, dear members of the forum! Bakery experience - about 10 "loaves". Questions: 1) what does the setting of the size / volume of the laid products affect when programming (choosing a program). Baking temperature? 2) crust setting - light, medium, dark. What changes when baking? Temperature in the last baking phase?

Good evening, dear members of the forum! Bakery experience - about 10 "loaves". Questions: 1) what does the setting of the size / volume of the laid products affect when programming (choosing a program). Baking temperature? 2) crust setting - light, medium, dark. What changes when baking? Temperature in the last baking phase?

All answers can be found here:
Bread Kneading and Baking Basics https://mcooker-enm.tomathouse.com/index.php@option=com_smf&board=131.0
UNDERSTANDING BREAD IN HOMEMADE BREAD #
Debriefing and questions here Bread did not work out again, I did everything strictly according to the recipe. What can be wrong? https://mcooker-enm.tomathouse.com/index.php@option=com_smf&topic=146942.0

It is necessary to distinguish between the "weight of the finished bread" on the display x / oven and the amount of flour and other ingredients.
"weight of finished bread" is needed to set the time for baking bread in a x / oven, this indicator is a conditional number, since the actual set and weight of ingredients never coincide with the weight on the display.

The weight of the finished bread depends more on the amount of flour + other ingredients.

I am interested in a purely technological moment, when we change the settings in size (in my bakery, according to the instructions, it depends on the flour mass of 400, 500 or 600 g) or the color of the crust (I have three degrees), what changes in the baking mode? Al

I am interested in a purely technological moment, when we change the settings in size (in my bakery, according to the instructions, it depends on the flour mass of 400, 500 or 600 g) or the color of the crust (I have three degrees), what changes in the baking mode? Al

Answered above: It is necessary to distinguish between the "weight of the finished bread" on the display x / oven and the amount of flour and other ingredients.
"weight of finished bread" is needed to set the time for baking bread in a x / oven, this indicator is a conditional number, since the actual set and weight of ingredients never coincide with the weight on the display.
The ratio of the weight of the finished bread and the amount of flour https://mcooker-enm.tomathouse.com/index.php@option=com_smf&topic=115935.0

Topic 2. PROGRAMS AND STAGES (CYCLES) OF BAKERY FOR BAKING BREAD #

All links to the Basics of x / Baking I gave above in the post

Color is the color of the crust, it only affects the color of the crust!

For the life of me, I don't see the answer to my question. I do not have the weight of the embedded ingredients on the scoreboard at all, I choose three parameters before starting: 1 - the program (everything is clear here), 2 - the mass of the loaded mixture (I do it myself, without automation, depending on the mass of flour, 3 - the color of the crust. How changing the 2nd and 3rd parameters change the baking process? The process time depends on the first parameter, it is stable and does not change (I have 4 hours). Breadmaker Panasonic 2500. So sorry, until I saw the answer. I'm just INTERESTED .-)

Example:
there is a bread size of 900 grams on the board, which means that you need to take about 600 grams of flour for this bread, the rest will be other ingredients.
Or a countdown: you took 450 grams of flour according to the recipe, which loaf to put on the board x / baking oven - about 675 grams, or within 650-750 grams, depending on the indicators that are indicated on the board. It is impossible to pick up the indicators and actually the weight of the test with an accuracy of gramme.

I repeat, the weight of a loaf on the scoreboard x / stove is purely informational, it can fluctuate within 100 grams, which I showed in my example. Loaf weight is needed ONLY for baking time.

Everything has already been described and selected here The ratio of the weight of finished bread and the amount of flour https://mcooker-enm.tomathouse.com/index.php@option=com_smf&topic=115935.0

Dear moderator, I have questions about how the "bread machine" changes the baking mode (probably temperature) depending on the weight of bread I indicated and the "crust color" ... - (I'll have to experiment ....

[Tatyana]

Tatyana, please help me answer the question: what processes are responsible for the formation of a crust?
This year the theme of the Leonardo research competition is "Food is an object of scientific interest." My daughter has already found answers several times on my favorite site "Breadmaker", each time exclaiming: Mom, your favorite site again! We read this topic together with her, but some doubts remained: did we answer correctly. From the proposed options, we answered: No. 3 and No. 4. But maybe something else? Variants of answers: 1. swelling of starch molecules upon absorption of water; 2. strengthening the networks formed by gluten proteins; 3. denaturation of gluten molecules; 4. destruction of starch molecules to dextrin and maltose; 5. polymerization of unsaturated fats; 6. interaction of simple sugars with amino acids and proteins.

[Maillard reaction]

what processes are responsible for crust formation?

If we talk about a beautiful, ruddy crust - there is such a thing as "Maillard reaction".

Maillard reaction (sugar-amine condensation reaction, English Maillard reaction) - a chemical reaction between an amino acid and sugar, which usually occurs when heated. An example of such a reaction is frying meat or baking bread, where the typical smell, color and taste of cooked food is produced during the heating process. These changes are caused by the formation of products of the Maillard reaction. Together with caramelization, the Maillard reaction is a form of non-enzymatic browning (browning). It is named after the French chemist and physician Louis Camille Maillard, who was one of the first to study the reaction in the 1910s.

And this is easy to verify in practice.
It is enough to bake bread completely without sugar
Bake bread according to the usual recipe, with a sugar content The amount of flour and other ingredients for making bread of various sizes
Bake bread with a high sugar (honey) content

Summary: the more sugar in the dough and bread, the darker the crust will be.

Thanks for the help . So, # 6 is also correct