Baking cookies and biscuits

Baking cookies and biscuits
In the process the production of cookies and biscuits baking is the most difficult phase.
During baking there are complex physical and chemical changes in the colloid and test, resulting in the formation product with their usual taste and texture.
It is no exaggeration if we say that the quality of cookies and biscuits to a large extent depends on the baking process.
Bakery products. The main parameter that determines the heating of the test and removal of excess moisture from it, is the temperature of the steam-air environment of the baking chamber.
In the process of heat transfer dough pieces with the heating surface of the furnace and the steam-air mixture in the baking chamber heating test occurs, characterized by changes in the various layers of the test temperature.
After about a minute of baking, the surface layers of dough pieces reach temperatures around 100 ° С, while the temperature of the inner layers of the dough does not exceed 70 ° С for the same period of time. As the dough warms up, the temperature of the surface layers rises steadily, but with less intensity and reaches the end of baking, it reaches 170 — 180 ° С. The temperature of the central dough layers also rises and reaches the end of the baking process 106 — 108 ° С.
Warming up the dough is accompanied by a change in the moisture content of the dough pieces as a result of evaporation of moisture from the surface layers.
Dehydration dough in the baking process is uneven and characterized by three periods.
In the first period there is intense heating of the test, so that water yielding rate increases and is variable in nature. By the end of the first period, the difference in moisture external and central layers of dough more increased as a result of dehydration of the surface layers of the test.otsadochnie i formovochnie mashi otsadochnie mashini dvuhbunkernaya mashina multidrop.large92
In the second baking period, moisture recovery occurs at a constant rate. Moisture removal occurs by evaporation at a temperature exceeding 100 ° С, with a gradual deepening of the evaporation zone inside the dough-biscuit, which is accompanied by a sharp increase in the volume of the biscuit.
In the third period of baking water yielding speed gradually decreases and evaporation zone reaches the central-layer cookie dough. In this period there is a removal of bound moisture and the formation of a crust.
In the first and second periods of warming happening dough with moisture evaporation from the surface layers in the absence of moisture migration from the inner layers to the surface, which is characteristic of the baking process. Thus the amount of moisture in the central layers increases slightly as a result of moisture migration from peripheral to central-layers of cookie dough. In the third period there is moisture migration from the inner layers to the surface, which is characteristic of the drying process.
Thus, baking cookies is a combined baking-drying process.
The intensity of the water yielding in the baking process depends on several factors.
Studies have shown that increasing the temperature of the baking chamber environment leads to an increase in the intensity of moisture output and a significant reduction in the duration of baking. This does not mean that during the whole baking process it is necessary to maintain the high temperature of the baking chamber environment. For each baking period, the optimum temperature of the medium must correspond. So, in the first period of the baking process there should be a low temperature of the baking chamber environment, so that a crust on the surface of the test billets does not form prematurely, preventing evaporation of moisture and lifting of products. In the second period of the baking process, the heat exchange should be increased, so the temperature of the baking chamber environment should be maximized. In the third period, the temperature of the medium must be reduced, since the process is characterized by a decrease in the rate of moisture transfer. An increase in the temperature of the medium in this baking period can lead to charring of the surface of the products.
The need to reduce the temperature in the first baking period can be compensated to a certain extent increase the relative humidity of the air environment steam baking chamber, heating with mixing dough through vapor condensation on the test surface and thus release the latent heat of condensation. Due to this intensified removal of moisture from the dough.
Moreover, moisturizing medium baking chamber leads to improved product quality: gloss appears on the surface of articles of improved color and porosity.
Increasing the thickness of the dough pieces extend baking process. With the increase in the thickness of the dough increases the resistance of the heat passing through the dough. Furthermore, increasing the thickness of the test environment temperature forces lower baking chamber.
The density of the test affects the length of the baking. Good garnetted dough is baked faster than dense.
A study of the baking of short-wave infrared cookies by radiation both from ceramic surfaces heated by gas and from lamp radiators showed that this baking process is fundamentally different from baking in conventional gas ovens. This method has two baking periods: in the first period there is an intensive warming up of the dough, and in the second - the removal of free and bound moisture.
Due to the penetration of heat rays inside the cookie to a depth of about 2 mm observed a more uniform distribution of temperature and humidity in the test, cookies and baking process is intensified.
Physical and chemical changes in the dough during baking. In the baking process, physical and chemical changes of the dough occur. Particularly significant changes undergo proteins and starch flour, which play a major role in the formation of the structure of cookies. When the dough is heated to a temperature of 50 — 70 ° C, the protein substances of the dough denature and coagulate, freeing up the water absorbed during swelling, and the starch swells and partially pasteurizes with the released water.
Dehydrated and coagulated gluten proteins and partially gelatinized starch form a porous skeleton, on the surface of which fat is adsorbed in the form of thin films.
At temperatures around 60 ° C, ammonium carbonate decomposes with release of gaseous substances - ammonia and carbon dioxide. Bicarbonate soda decomposes at a temperature of 80 — 90 ° С with evolution of carbon dioxide. As the dough temperature rises, the pressure and volume of gaseous products formed increase, resulting in a change in the volume of dough pieces, and the pores in the dough increase significantly. In loosening the dough, an important role is played by the water vapor formed in the dough during the baking process.
In the baking process, there is a gradual dehydration of the surface layers and the formation of a crust on the surface of the dough. It is very important that the formation of a crust did not occur immediately, but gradually, since its appearance prevents the increase in the volume of dough pieces. Therefore, the baking process is first carried out at a low temperature with the moistening of the medium of the baking chamber, which contributes to the formation of a thin crust in a later period.
During the baking process, chemical changes occur in the dough. There is a decrease in the amount of sugars in cookies, which is explained by their partial decomposition under the influence of the high temperature of the environment of the baking chamber. The decisive role in the color of the crust of biscuits belongs to the products of the interaction of reducing sugars with the degradation products of proteins, i.e., melanoidins. Along with this, the color of the crust and the products as a whole is influenced by bicarbonate soda, the presence of which gives the products a yellowish color in the baking process.
The total protein content in cookies during baking almost does not change, but for certain types of proteins, significant quantitative changes are observed. Such changes are undergoing individual types of protein, are the result of temperature exposure to them in the baking process.
The amount of insoluble starch decreases, due to its partial hydrolysis during baking and form a soluble starch and dextrin.
Also reduced the amount of fat that should be explained by the release of fat from the test result in unstable adsorption of it to the surface of the micelles.
Alkalinity of biscuits during baking is significantly reduced, apparently due to the interaction of alkaline chemical disintegrating agents with substances having an acid reaction, and also partly as a result of the volatilization of ammonia formed during the decomposition of ammonium carbonate.
Mineral content is not changed in a baking process. The amount of organic phosphorus is reduced.
Optimum baking mode. When choosing the optimum baking mode, it is necessary to take into account the influence of the parameters of the vapor-air medium of the baking chamber on the colloidal and physicochemical processes that take place in the dough, which determine, ultimately, the production of products with strictly defined quality indicators. Along with this, it is necessary to provide optimal conditions for heat exchange in the baking chamber, allowing the process to be most productive and economical.
The results of experimental studies allow us to recommend the following optimal mode of baking cookies.
At first, the baking process should occur at high relative humidity (60 — 70%) and a relatively low temperature (not higher than 160 ° C) of the baking chamber medium, which favors the flow of colloidal and physicochemical processes under optimal conditions.
The high relative humidity of the environment of the baking chamber, achieved by artificial moistening, intensifies the dough heating, which promotes the beginning of the process of denaturation of proteins and the partial gelatinization of starch, as well as the decomposition of chemical disintegrating agents with the release of gaseous products that loosen the dough.
The low temperature in combination with the high relative humidity of the environment of the baking chamber eliminates the possibility of the formation of a crust on the surface of the products in the first baking period. The elastic film formed on the surface of the products does not offer significant resistance to the expanding gases inside the dough pieces, which contributes to the gradual lifting of the products and, consequently, the formation of a porous structure.
The second baking period characterized by a variable temperature regime of the baking chamber environment, with a gradual increase in temperature to 350 — 400 ° С.
The relative humidity of the environment of the baking chamber can be reduced, thus moistening the baking chamber in this baking period does not produce.
In the second baking period, the colloidal and physico-chemical processes in the dough, associated with denaturation and coagulation of the protein, partial gelatinization of starch and decomposition of chemical baking powder, are mainly completed and completed.
The third period of baking characterized by a constant temperature, reduced to 250 ° C. In this period there is a final fixation of the structure of products with the formation of a crust on their surface and the process of removing excess moisture is completed.
The duration of baking cookies usually ranges from 4 — 5 min. In optimal mode, the baking time is reduced to 3,5 min.
For baking biscuits and crackers, a variable temperature regime is usually used with obligatory moistening of the medium of the baking chamber. The first 4 min baking chamber medium temperature gradually rises from 230 to 260 ° C, then gradually decreases to 205 ° C. The total duration of the baking process for simple biscuits 12 — 15 min, diet biscuits and crackers 5 — 10 min. Longer baking of biscuits as compared to cookies is explained by the fact that the moisture and thickness of the dough pieces of these products is higher, and the maximum temperature of the medium of the baking chamber is lower.
For baking pastry products used furnaces of various designs, which can be classified by the method of heating the baking chamber:
a) heat, heat accumulating walls of the baking chamber in the process of direct combustion of fuel in it;
b) channel, where the coolant is a gas formed during the combustion of fuel and transfers heat to the baking chamber through the walls of the channels;
c) with steam-and-water heating, where the Perkins tubes are the heat-giving surface;
d) tunnel with direct combustion of gas in baking chambers using burners or heated by electricity using heat-transfer surfaces in the form of resistance elements.
According to the design of the baking hearth distinguish ovens with stationary, sliding and conveyor hearth.
The most mechanized are furnaces with conveyor hearths, which are also divided into the following main types: a) chain, b) lyulechnye, c) carousel, d) belt.
Typical equipment for baking cookies are continuous tunnel gas ovens with conveyor chain or belt hearths.
In the case of using tunnel furnaces with conveyor chain hearths, sheets with dough pieces are mounted on chain conveyors that move along the furnace and are heated by two rows of burners located above and below the conveyor.331
Fig. 93. Gas stove for baking pastry products.
However, in recent years, these ovens have been supplanted by more advanced tunnel gas ovens of continuous action with perforated or mesh steel ribbons, in which dough pieces are placed directly on the baking chamber ribbons. Preference is given to single-belt furnaces (fig. 93).1907694
Adjustment of speed of advancement of the conveyor is carried out by a variator or a speed controller. Gas burners are located in the baking chamber in accordance with the requirements of the technological mode of baking. A higher temperature of the medium in a certain zone of the baking chamber is achieved by a more frequent arrangement of the burners. In addition, the ambient temperature of the baking chamber can be adjusted by changing the gas supply to the burners until the shutdown of some of them.
Gas tunnel ovens also have the advantage that the baking chamber is heated to operating temperature in 2 — 3 hours, while in channel-type ovens it takes 2 — 3 days. In case of urgent repair, these furnaces are also cooled in the shortest possible time.
Electric ovens have advantages over other designs of ovens and in the near future will be introduced at enterprises producing flour confectionery products, especially in areas with cheap electricity. In these ovens, the heat mode is more easily and automatically regulated, the possibility of an explosion in the baking chamber (which may occur in gas ovens) is eliminated, there are no combustion products, the efficiency of the oven is increased.
Furnaces with stationary hearth are used only in small enterprises in the development of a wide range in small quantities, requiring different temperature conditions. These furnaces are characterized by low productivity, low efficiency, large dimensions, manual loading and unloading of products, therefore, recently they are replaced by channel-heated furnaces.
The oven designs developed by the VKNII staff ensure optimal baking of flour confectionery products and different performance.
Cool cookies and biscuits
Products after baking at the time of removal from the oven have a relatively high temperature; the temperature of the inner layers slightly exceeds 100 ° С, and the temperature of the surface layers of the cookie reaches 118 — 120 ° С. Attempting to remove products from stencils or steel tapes at this temperature leads to a violation of their shape.
To give the products some mechanical strength, which allows for the removal of products from stencils or steel strips, they are cooled. Products baked on stencils are cooled on fixed or rotating racks to temperatures of 50 — 70 ° C, after which it becomes possible to remove or knock down products from stencils without disrupting the shape of the products.
When baking cookies on perforated or mesh steel tapes, pre-cooling to a temperature of 50 — 70 ° C is carried out on the part of the conveyor protruding from the oven. The products acquire some strength, which allows them to be mechanically removed from the steel strips of the furnace and transferred to a cooling conveyor for final cooling due to heat transfer to the environment.
Cooling cookies on open conveyors, used in some enterprises, cannot be considered rational, since their length often reaches several tens of meters, which clutters up production facilities.
It should be borne in mind that products should be cooled under a relatively mild mode in order to avoid overvoltages in them, often leading to the formation of cracks. Cooling temperatures that are too low can cause cracks in the products. Different humidity in the surface and internal layers of cookies leads to an intensive redistribution of moisture inside the products after baking. As a result, there is a change in the linear dimensions of the individual layers of cookies, which leads to cracking of the products.
The duration of cooling cookies is greatly influenced by the speed of the cooling air. The higher the speed of the cooling air, the faster the process of cooling the cookies.
The ambient temperature also affects the duration of cooling cookies, but to a lesser extent than the air velocity.
The following optimal cooling conditions for cookies are recommended: medium temperature 20 — 25 ° С, cooling air velocity 3 — 4 m / s. It is most advisable to cool the cookies on a closed type conveyor with forced air circulation. Initially, the cookie is cooled in the chamber on the conveying part of the conveyor to 50 — 70 ° C, and then with the help of knives that fit tightly to the conveyor, the cookie is easily, without deformation, separated from the conveyor and transferred to the second cooling conveyor of the closed type, where the final cooling is performed cookies with the same parameters up to temperature 32 — 40 ° С.
The length of the cooling conveyor is significantly reduced and can be extended to 4 — 8 m, depending on the furnace performance, provided that the products are pre-cooled on a protruding furnace tape of length 2 — 4 m.
The cooling of the cookies is accompanied by the process of moisture loss due to the heat accumulated by the products during baking. However, the heat supply in the products is limited; therefore, as the products are cooled, the removal of moisture slows down and then stops completely.
Finishing and packaging of cookies and biscuits
After cooling some of the product is exposed to the exterior.
The finishing gives the products an attractive look and gives them a pleasant taste. Finishing can also protect products from environmental influences.
The surface of certain kinds of sugar cookies coated with chocolate icing that is carried out on the enrobing machines commonly used in the production of candy, or manually.
Hand enrobing is done by dipping the biscuits in chocolate icing so that the icing completely or partially covers the surface of the biscuit. After that, the glazed cookies are cooled on the grids at the temperature 5 — 8 ° С; an excess of glaze flows down from the biscuit, and the glaze layer acquires the necessary hardness.
Some of the sugar cookies are produced with a layer of fruit or cream filling and is called puff pastry. The biscuits are sandwiched by spreading or jigging the filling from the syringe bag onto the bottom surface of the biscuit, on top of which the second biscuit is placed with a pattern upwards. Spreading and gluing cookies is done using special tools or manually.
The most commonly used machine, which has a platform with a cutout corresponding to the size of the cookies. The bottom side of the cookie is pressed under the cut-out area, and from above through the cutout with a spatula, put the filling on the surface of the cookie. The thickness of the filling layer is equal to the cross-section of the machine platform. On the biscuits with the filling is placed the bottom side of the second cookie, lightly pressed, cooled or stand and sent for laying.
Some varieties of butter biscuits are subject to decoration. Thus, part of the sand-jigger grades of butter biscuits are sandwiched with a filling, and then glazed with sugar syrup or partially with chocolate.
Some varieties of sand-rich sweet biscuits are glazed partially or completely with chocolate or, along with the glazing, sprinkle the surface with chopped nuts. Other varieties of this group are covered with powdered sugar. Biscuit-whipped varieties of butter biscuits are also subjected to interlayer and gluing together with filling, while protein-whipped varieties are glazed with chocolate.
The surface of individual varieties of macaroons is decorated with fruit filling and sprinkled with almonds or crumbs.
Packaging. Materials used for packaging products should be as resistant to external influences. Cookies are a hygroscopic product, therefore it is very important to use paper with low water and moisture permeability for wrapping. Waxed paper has the best water and moisture impermeability. However, waxed paper is unsuitable for products containing a significant amount of fat, since fat dissolves paraffin. Products with high fat content should be wrapped in greaseproof paper - parchment or transparencies. Of the transparent films, cellophane is the most common, which has good grease resistance, but poor moisture resistance. Recently, varnished cellophane has been used for wrapping products, which, along with good grease resistance, has satisfactory moisture resistance.
Products with a limited content of fat are usually wrapped in parchment, asphalt or waxed paper.
Cookies are wrapped in bundles, packaged in boxes, and for intracity consumption in paper or plastic bags.
Cookies are usually wrapped in two layers of paper: a roll-in - in one of the listed types of packaging materials and a colorful label made of writing paper. Biscuits, in addition, are wrapped in a third layer of cardboard, which is between the roll and the label. When using cellophane, the cookies are wrapped without a paper tuck. Wrapping biscuits and biscuits are most often produced on semi-automatic machines.
Butter biscuits and crackers are placed in boxes. The boxes are covered with greaseproof paper to avoid the appearance of fatty spots on the boxes.
When packing cookies directly into boxes, the inner sides of the box should be lined with paper, and each horizontal layer of cookies should be covered with a sheet of parchment paper, waxed or wrapping paper.
Packs, boxes and bags of cookies packed in boxes - plank, plywood, corrugated cardboard and paper casting.
Cookies and biscuits sent to areas of the Far North, or for special purposes, are packed in tin hermetically sealed boxes or in corrugated cardboard boxes covered with a layer of paraffin.

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