Basic methods of heat treatment of meat. Heat treatment of meat

Denaturation of meat muscle proteins during heat treatment significantly affects the properties of finished products. During denaturation, sarcoplasmic proteins form a continuous gel, and myofibrillar proteins, already in the gel state, become denser. In this case, the diameter of muscle fibers decreases by 36-42%, the tissues become denser, and the cutting resistance in the transverse direction increases. During boiling, the fabrics are more compacted than during frying, since in the latter case the temperature in the center of the pieces is lower and the processing time of the raw materials is shorter.

The myoglobin molecule, which gives the red color to raw meat, contains a chromophore group (causing the color) - heme. During denaturation, the ferrous ion entering it is oxidized. In this case, heme is formed from heme, which causes the gray color of the meat. The change in the color of beef begins at a temperature of 60 ° C, at a temperature of 60 to 70 ° C, the red color weakens and, with a further increase, turns into a gray-brown. As a result, the color of meat and its juice to a certain extent can serve as an indicator of the degree of its heating.

Myosin is completely denatured at a temperature slightly above 40°C, and 90% of the remaining meat proteins are denatured at 65°C. However, to achieve culinary readiness, it is necessary to heat the meat during frying to a temperature of 80-85 ° C, and during cooking - to a temperature of 95 ° C for some time. At the same time, denatured proteins partially undergo deeper changes with the formation of hydrogen sulfide, hydrogen phosphide, mercaptans and other volatile substances. Part of the amino acids is destroyed and reacts with melanoidin formation. Therefore, too long heat treatment can reduce the nutritional value of meat.

The methods of heat treatment and its timing are determined by the properties of the connective tissue. Culinary readiness occurs when 20-45% of collagen is converted to glutin. In this case, the cutting resistance is significantly reduced. From here, it is better to fry only those parts of the meat in which this process has time to occur before the product dries and begins to burn.

In the meat of young animals, there are much fewer connective tissue proteins than in the meat of adult animals, and their collagen turns into glutin much faster. Therefore, almost all parts of veal are suitable for frying.

In beef, tenderloin, thick and thin edges, upper and inner pieces of the hip part are used for frying, and the hem, brisket, scapular and subscapular parts, etc. are suitable only for stewing and cooking.

In some parts of the carcasses of small livestock, the difference in the structure of the connective tissue is much smaller and it itself is less stable during heat treatment. Therefore, pork ham, loin are also suitable for frying, and brisket is also suitable for lamb.

Losses of biotin, folic acid and vitamin Bi2 are insignificant, losses of vitamins B2 and PP usually do not exceed 15-20%. Vitamin Bi is destroyed somewhat more (25-32%). Vitamin Be is the least stable, and its losses reach 40-50%.

The mass of semi-finished meat products changes significantly during heat treatment. Weight loss is 35-40%. This is mainly due to three reasons: the release of moisture (30-35%), the rendering of fat (about 5%) and the loss of soluble substances as a result of diffusion and juice release (an average of 1-2% of the mass of meat).

The release of moisture during the heat treatment of meat is caused by the fact that during the denaturation of proteins their ability to retain water decreases, and the contraction of collagen fibers (welding) leads to a decrease in the geometric dimensions of semi-finished products and the extrusion of released moisture from them.

The specific taste and aroma of boiled and fried meat are due to a number of soluble and volatile substances, most of which are formed during heat treatment. First of all, free glutamic acid should be mentioned, which is split off from complex compounds when meat is heated. Its solutions have a taste close to the taste of meat broth. Accumulate in meat during heat treatment and other products of protein hydrolysis (peptides, amino acids), nitrogenous bases (creatine, creatinine, etc.), which also form the taste meat dishes. The aroma of fried and boiled meat is also due to the content of volatile substances such as aldehydes, ketones, amines, mercaptans, sulfides, etc.

During the heat treatment of offal, the same processes occur as in the processing of meat, but their nature is somewhat different. So, the language during cooking emits only 25% of the moisture contained in it. This is due to the high content of collagen in the skin, which absorbs a significant part of the water released by muscle proteins. The mass of the brain also changes little during heat treatment, and the kidneys lose moisture much more than meat. In addition, the kidneys during cooking lose almost 1.5 times more soluble substances than meat and tongues. Despite this, their decoctions are not used, as they have an unpleasant taste. The least amount of soluble substances is released when brains are cooked. Therefore, their decoctions are tasteless.

Dishes from boiled meat and offal

General rules for cooking meat. The second boiled dishes are prepared from all types of meat, tongues, kidneys, liver, udder and other offal, corned beef, smoked brisket or loin, ham, sausages, sausages and sausages. From beef carcasses for the preparation of boiled second courses, a shoulder blade, a subscapular part, a hem (from carcasses of the I category of fatness) are used; from lamb and goat carcasses - brisket, shoulder blade, ham; from pork carcass - shoulder blade and brisket (entirely natural). At the brisket, a film is cut on the inside to facilitate the removal of bones after cooking. The pulp of the shoulder blade is rolled up and tied with twine.

The meat is cut into pieces weighing no more than 2 kg, since larger pieces are cooked unevenly. Water for cooking is taken at the rate of 1-1.5 liters per 1 kg of meat. The prepared meat is placed in boiling water and, when the water boils again, they continue to cook at a very low boil or without boiling at a temperature of 85-90 ° C. 30 minutes before readiness, put onions, parsley, celery, carrots, and 10-15 minutes before spices. About 15 g of vegetables are put per 1 kg of meat, bay leaf - 0.1 g. Salt is added along with spices - 10 g per 1 kg of meat. The meat cooked in this way is juicy, with a pleasant aroma and taste.

Cooking time depends on the density and amount of connective tissue, the thickness of the pieces, the age of the animals.

The average cooking time is:

Beef……………………………….2 h - 2 h 45 min

Lamb……………………………….1.5 h - 2 h 10 min

Pork………………………………… 1 h 45 min - 2 h

Veal………………………………..1 h 20 min - 1 h 45 min

The readiness of the meat is determined by a puncture with a chef's needle in the thickest part of the piece, while the needle should freely enter the meat, and transparent juice should stand out from the puncture. The meat of older animals requires a longer cooking time.

Bones are immediately removed from the brisket after cooking. Store the meat in a sealed container with a small amount of broth at a temperature of 50-60°C. If the meat needs to be stored for more than 3 hours, then after cooking it is quickly cooled, covered with a wet cloth, and stored at a temperature of 4-6°C. As demanded, the meat is cut across the fibers into pieces, placed in a shallow dish, poured with broth and brought to a boil.

Corned beef is cooked in pieces weighing 1.5-2 kg. After soaking, it is poured with cold water at the rate of 3-5 liters per 1 kg of meat and boiled at a low boil. After 1.5-2 hours, roots, spices are laid and cooked until tender. Broths from cooking corned beef are used for cabbage soup from sauerkraut and borscht.

Weight loss during cooking meat is on average 40%. Extraction of soluble substances is due to two reasons: extrusion and diffusion. The amount of soluble substances released as a result of diffusion depends on the ratio of water and meat, the size of the pieces and the cooking time. So, with a ratio of meat and water of 1: 1, about 2.34% of dry substances are lost from the total mass, and more soluble substances are extracted due to diffusion.

The maximum temperature in the center of a piece of meat when bringing it to readiness should be 75-80°C. Further heating increases the loss of moisture, reduces the juiciness of products, and worsens their quality.

The cooking mode and the temperature of the cooking medium are of great importance. If you cook meat at a boil, then the protein gels are strongly compacted, a lot of moisture is squeezed out and the quality of the products decreases. When cooking without boiling, moisture is pressed out by 2-3% less, and the loss of extractives is reduced by 20-25%. The temperature of cooking by-products is not significant.

The meat is boiled. Boiled meat is cut across the fibers in 1-2 pieces per serving. Boiled beef is garnished with a complex side dish, consisting of boiled potatoes (whole medium-sized tubers or turned into barrels), boiled vegetables, cut into large cubes (carrots, turnips), stewed white cabbage, rolled into balls, onions stewed whole small heads or chopped slices. The meat is placed on an oval dish or plate, the side dish is placed on the side and decorated with sprigs of greens. Boiled meat can also be served with other side dishes: potatoes in milk, mashed potatoes, vegetables in milk sauce.

Beef and pork are released with sauces sour cream with horseradish, Madeira, sweet and sour with nuts; lamb - with white sauce with egg, sour cream with horseradish; veal - with steam and white sauce with egg.

Boiled tongue. Tongues prepared for cooking are placed in a bowl, roots, onions, salt are added and poured with boiling water. Cook at a low boil until tender. Boiled hot tongues are dipped in cold water for 5 minutes and cleaned. Peeled tongues are cut into portions of 2-4 pieces, poured with broth and brought to a boil. The tongue is served with mashed potatoes, green peas, boiled vegetables, poured with melted butter or red sauce with wine, sour cream with horseradish or red.

Meat cooking

The meat is boiled in water or in a decoction of vegetables. If the meat is placed in boiling water, the top layer of proteins quickly coagulates, which prevents the substances that make up the meat from becoming liquid. If the meat is put in cold water, these substances in the predominant part pass into the broth. We are talking about soluble proteins, mineral salts and some other substances. Proteins that have passed into the broth coagulate under the influence of high temperature and form the so-called foam. The foam should not be skimmed off as it has nutritional value and removing it reduces the nutritional value of the broth.

It should be remembered that basically the richness of the broth and the quality of boiled meat depend precisely on the ratio of the amount of meat and water, and not on the method of laying. Therefore, you should choose the right size dishes.

When cooked, about 35% of the liquid contained in raw meat goes into the broth, and for the most part the first 15 minutes of boiling. That is, the broth becomes more in volume, and the meat is much less. Therefore, you should not strive to completely cover the meat at the beginning of cooking.

Cooking should be carried out under a tightly closed lid with a minimum boil - so that the steam floats "along the bubble". This boiling prevents the emulsification of fat and the appearance of a greasy taste in the broth. And under a tightly closed lid, the steam squeezes out the air and ensures the virtual absence of fat-oxidizing oxygen. In French cuisine, for greater compaction, after boiling, before the final closing of the lid, the edge of the pan is sometimes even smeared with batter.

Cleaned and washed meat is placed in boiling slightly salted water with spices. Salt prevents meat juices from completely becoming liquid. The water should cover the meat. The pot must first be put on high heat, quickly brought to a boil, then cook the meat over low heat under the lid. When the foam disappears from the surface, add peeled vegetables and cook until fully cooked, salt at the end of cooking (10 minutes before the end).

Any addition of water during the cooking process is unacceptable, because it irreparably worsens the taste of both the broth and meat.

After cooking without opening the lid, the meat should be allowed to brew for 10 minutes. Then immediately put the finished meat out of the broth (so as not to get wet) and wrap it tightly in foil (for storage) or immediately serve it on the table, cut into portions and sprinkle with hot broth (it can also be mixed with a small amount of butter) to prevent drying out.

MEAT IN SAUCE

Meat to be served with sauce should be boiled with the bone in a small amount of water. The meat should be put in boiling salted water and peeled vegetables should be added in the middle of cooking. Separate the finished meat from the bone and cut into portions. On the resulting broth, prepare the sauce (with flour dressing, with sour cream, etc.).

COOKING SMOKED MEAT

Smoked meat before cooking should be washed, then put in boiling water. The water should cover the meat. Counting from the secondary boil, the meat is cooked from 1 to 3 hours, depending on the size of the piece. Water should be added as it evaporates.

The readiness of the meat is determined by a fork. Put the finished meat out of the broth after the final cooling.

For cooking meat, dishes made of durable material are used. Cast iron cookware with a lid is also suitable for this purpose.

Dishes from cutlet mass. Cutlets and meatballs are made from cutlet meat (beef, pork, veal), as well as rabbit and wild goat meat. Homemade cutlets are made from equal amounts of beef and pork with the addition of onions and melange. The composition of amateur cutlets includes eggs, and Moscow cutlets - raw lard and sautéed onions. Filled schnitzels are made from beef, veal, pork. Products are fried on baking sheets or pans with fat on both sides, and then brought to readiness in an oven (4-5 minutes). In case of mass production of dishes, frying in an oven with a temperature of at least 250-280 ° C is allowed, while they are fried for 4-5 minutes, turned over and put back in the oven for 4-5 minutes. The readiness of chopped products from the cutlet mass is determined by the fact that bubbles appear on their surface, and when pressed, a transparent colorless juice is released.

Oriental beef (prepared beef 150g with chopped fresh cucumber 30g watered soy sauce, sprinkled with spices for the steak and fried until tender in the main way, served on an El plate with a side dish)

Escalope (a beaten piece of pork is dipped in oil with spices and fried on a preheated grill-pan until cooked, served on an El plate with a side dish).

Pork with mushrooms (beaten pork is breaded in flour and fried in the main way until a golden crust is formed, after which 15 g of browned onions, 20 g of browned mushrooms are spread on top, sprinkled with 20 g of cheese and baked in a combi steamer for 7 minutes)

Pancakes with minced meat (200 g of minced meat are fried together with 15 g of brisket and 30 g of spicy carrots are fried for 2-3 minutes, removed and laid out in baking dishes, the remaining minced meat is spread on 3 pancakes and wrapped in a triangle, tomatoes are lightly fried 100 g and spread in a mold on minced meat , pancakes with minced meat on top, cheese sauce 100g, 25g grated cheese and baked for 8 minutes in a combi steamer.Served in molds on a small dinner plate with a napkin).

Sausage "Zvychaynaya" (p / f sausage is placed in boiling salted water and boiled for 10 minutes until tender, after which it is removed from the container and transferred to a tray. Used for various dishes).

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Content
Introduction
1. Purpose of heat treatment
2. Changes in physical and chemical parameters and biological value of meat and meat products during heat treatment

2.1 Changes in meat proteins during heating
2.2 Change in fat when meat is heated
2.3 Modification of extractives
2.4 Vitamin changes
2.5 Change in water holding capacity

3. Color formation
4. Formation of taste and smell
5. Organoleptic indicators
Conclusion
Literature

Introduction

Heat treatment- one of the most frequently used technological processes in meat production. The main purpose of heat treatment is to bring the product to a state of culinary readiness. Since this increases the resistance of the product to microbial spoilage, heat treatment is used as one of the preservation methods. Meat and meat products are usually heated from 60 to 180 "C. The action of high temperatures (above 100" C) is the most reliable method of preservation, which makes it possible to obtain canned food that can be stored for 3-5 years. At lower temperatures, the barrier effect of heat treatment is reduced, which affects the shelf life. So, boiled products cannot be stored for a long time, they should be quickly sold.

Thermal treatment of products is carried out in different ways: immersion in a liquid medium, exposure to a steam-air mixture, live steam, electric contact heating, microwave energy, infrared heating, as well as a combination of these methods.

According to the technological purpose, these methods can be divided into basic and auxiliary.

Under the main methods of heat treatment is understood such a change in the properties of the product, as a result of which it becomes suitable for food (sausages and culinary products, canned food) or passes into another qualitative state (fat rendering, gelatin extraction, etc.).

Auxiliary methods include those in which the processed raw material does not undergo significant changes (scalding, singeing, drying, etc.) or acquires specific properties (roasting, blanching, etc.) necessary for the production of the corresponding product. Such treatment generally has a negligible barrier effect.

Thermal preservation includes sterilization, pasteurization, boiling and baking.

Sterilization is the main link technological process in the manufacture of canned food. It consists in the heat treatment of meat at a temperature above 100 "C, as a result of which the microflora is destroyed.

Pasteurization is carried out at a temperature of 100 °C and below. It also ensures the microbiological safety of canned food and its ability to be stored. Pasteurized canned food has a shorter shelf life than sterilized canned food.

Cooking is widely used in the production of sausages, ham and other products. During the cooking process, up to 99% of the microflora is destroyed, so it does not guarantee the complete destruction of microflora and especially spores. Therefore, cooked foods cannot be stored for a long time, they should be quickly sold.

Sterilization and cooking is carried out in a humid heating medium (water, steam, steam-air mixture). Baking is classified as a dry heating method.

Roasting is carried out with hot air to a temperature in the center of the finished product of 68-70°C, which, like during cooking, limits the shelf life of finished products.

1. Purpose of heat treatment

The main goals of heat treatment:

1) fix the structure of the meat product;

2) bring the product to a state of culinary readiness;

3) destroy vegetative forms of microorganisms and increase the storage stability of products;

4) to form the required organoleptic characteristics of the finished product (appearance, color, taste, smell, texture), - is achieved by using various technological methods with a specific purpose.

Heat treatment of meat and meat products causes structural, physicochemical and other changes in them, the depth of which depends on temperature.

2. Changes in physicochemical parameters and biological value of meat and meat products during heat treatment

In the process of heat treatment, complex changes occur in raw materials and meat products, associated with the penetration of heat into the product and ambiguously affecting the quality of the finished product (Fig. 1).

Rice. 1. Changes that occur in the product during heat treatment

The depth of these changes depends mainly on the temperature reached inside the product, the duration and method of heating, the presence of water in the product itself or in the heating medium, etc.

2.1 Changes in meat proteins during heating

When heated, a protein molecule undergoes complex physicochemical changes, primarily denaturation and coagulation, the depth of which depends on temperature, duration of heat treatment, and some other factors.

Proteins of animal origin are thermolabile: their denaturation begins at 40°C and rapidly increases with increasing temperatures. Basically, the process of denaturation of most muscle proteins is completed at temperatures of 68-70°C, and at 80°C, muscle proteins are almost completely denatured.

Denaturation of muscle proteins, welding and hydrothermal disaggregation of collagen find their external expression in the change in the structural and mechanical characteristics of the heated products, as well as their geometric dimensions.

During heat treatment of products with intact cellular structure, the integrity of muscle fibers is preserved, but they become denser and decrease in diameter due to protein denaturation. At the beginning of heating, the collagen fibers of the sarcolemma become transparent, their tortuosity decreases, and their thickness increases. At a temperature of 65 0 C, the bundles shrink, lose their fibrous outlines, become less dense, more vitreous. Areas with destroyed collagen appear, filled with glutin, and why the destroyed tissue acquires a granular structure. The degree of destruction depends on the properties of the connective tissue, temperature and duration of heat treatment. The coarser the connective tissue membranes, the more resistant they are to heat.

Heat treatment of meat containing a small amount of connective tissue leads to a compaction of the meat structure as a result of coagulation of muscle proteins.

Effect of temperature and method of heating on the rate and temperature of protein denaturation

The rate of thermal denaturation depends on temperature, humidity, heating method and other factors. Denaturation is inhibited by the addition of certain substances such as pyrophosphate, polyhydric alcohols, sugars, and P-actin, although the mechanisms of inhibition are different. The rate of ATPase denaturation increases with muscle protein breakdown as a result of a decrease in the size, density and symmetry of the molecules. The rate of protein denaturation also depends on some other factors. For example, the denaturation of fibrinogen with urea accelerates with an increase in the concentration of urea and with a decrease in pH below 7, however, in the pH range of 7.0...8.6, the reaction rate is almost constant. The presence of heavy water stabilizes the native structure of enzymes due to the presence of hydrogen bonds, reducing the rate of inactivation.

It has now been established that the proteins that make up meat denature as the temperature determined for each protein is reached (Table 1). Myosin is the most sensitive to heat. In the temperature range of 45...50°C, the main part of the structural muscle proteins is denatured. Sarcoplasmic proteins (myogen and myoglobin) denature at higher temperatures (55...70°C). The most resistant to denaturation are myoproteins (most of the enzymes), as well as hemoglobin, serum albumin, and collagen.

Table 1

It has been established that denaturation occurs in steps, i.e. when a protein reaches a certain temperature, it acquires an appropriate structure with certain properties.

Changes in charged groups and pH of proteins during the heat treatment of meat

In the process of thermal denaturation and subsequent coagulation, structural changes in proteins occur, the breaking of old and the formation of new bonds with the participation of hydrogen bonds, sulfhydryl, disulfide, acidic and basic groups of proteins and hydrophobic interactions.

R. Gamm showed that heating meat in water from 20 to 70°C causes a stepwise decrease in the number of carboxyl groups in myofibril proteins, while the number of main groups does not change significantly. Significant changes in acidic groups begin at 40°C. In the range of 40...50°C their number decreases, at 50...55°C it remains unchanged. At temperatures above 55°C, the number of acidic groups continues to decrease, and at a temperature of about 60°C, it decreases very significantly. The total reduction in the number of acidic groups upon heating to 70°C is 85%. At temperatures from 70 to 120°C, along with a further reduction in the number of acidic groups, a decrease in the number of basic groups begins.

The change in the ratio of charged (acidic and basic) groups as a result of denaturation and post-denaturation transformations is associated with a change in pH. At the same time, the fact of a direct correlation between the pH value of raw materials, water-holding capacity and the yield of the finished product has been established. The higher the initial pH value of the raw material, the better the quality (juiciness) of the finished product. The magnitude of the pH change depends on the temperature and method of heating, the initial pH value of raw meat.

The anatomical origin of the muscles also influences the magnitude of the pH shift. With an increase in the heating temperature, the water-retaining capacity changes and the isopoint of fibrillar proteins shifts to higher pH values, and the number of main groups increases. During thermal denaturation, the isopoint also shifts to higher pH values, apparently due to the splitting of hydrogen bonds and the release of additional positive charges.

Change in the solubility of muscle and disaggregation of connective tissue proteins

The solubility of proteins is one of the indicators characterizing their denaturation changes. It is known that heating is accompanied by a decrease in protein solubility. The intramolecular bonds broken during denaturation interact intermolecularly, resulting in particle aggregation. In other words, denaturation changes in protein macromolecules, changing the surface layer of the molecule, lead to a violation of the ratio of hydrophilic and hydrophobic groups in the direction of increasing the latter, which leads to a decrease in solubility.

With traditional methods of heating, the precipitation of sarcoplasmic proteins is observed at a temperature of about 40 ° C, and most strongly at pH 5.5. The bulk of these proteins coagulates in the range of 55...65°C. There is evidence of the presence of heat-resistant proteins: for example, adenyl kinase can withstand temperatures of about 100°C.

The change in collagen under the influence of heat is a complex process that consists of two stages: welding and hydrolysis of collagen. Collagen is a glycoprotein in which the content of covalently linked carbohydrates varies depending on the source of the protein. The soluble part of collagen - procollagen and the insoluble part - collastromin differ in denaturation temperatures and the nature of denaturation transformations. The denaturation of procollagen proceeds in two stages and ends at a temperature of 36.5°C, forming a homogeneous transparent mass that passes into solution. Collastromin passes into a homogeneous state at a higher temperature or with a longer heat exposure.

In the temperature range of 62...64°C, when heated in water, collagen fibers are instantly wrinkled, which, folding three times in relation to their original length, turn into a rubber-like mass. In the process of wrinkling, the three-helix structure of the peptide chains of individual collagen molecules takes the form of a ball. However, unstructured peptide chains are still bound by covalent bonds and cannot go into solution.

As a result of moist heating of collagen-containing tissues, polydisperse degradation products are formed. With slow heating, macromolecular compounds predominate, with intense heating, compounds with a lower molecular weight. When welding collagen, about 60% of the mucoids contained in the tissue pass into the solution.

Since welding and hydrothermal disaggregation of collagen reduce strength properties, meat containing a lot of connective tissue becomes less rigid after heating. However, if the degree of destruction of the tissue structure is too great, the meat breaks up into separate fibers due to a violation of the connection between the bundles of muscle fibers, united by connective tissue layers.

It follows that the achievement of the culinary readiness of the product must meet a certain degree of collagen breakdown, sufficient to soften the tissues, but not more than the one at which their noticeable decay begins. According to the Institute of Nutrition of the Russian Academy of Medical Sciences, the state of culinary readiness is reached when 20-45% of connective tissue collagen breaks down.

For products that contain little connective tissue, culinary readiness is determined by the denaturation of soluble proteins, since with an increase in heating time, their rigidity and tissue dehydration increase. In practice, it is enough to heat the product to the full depth up to about 70°C.

Several other factors also influence the disaggregation of collagen during heating. The shift in the pH of meat from the isoelectric point enhances disaggregation, an increase in the age of animals from one to one and a half years reduces it by about 2 times. Thus, the degree of collagen disaggregation and the formation of degradation products depend not only on the temperature to which the product is heated, the state and composition of the meat, but also on the speed, and, consequently, on the method of heating.

Protein coagulation and its influence on qualitative changes and structure of meat products

The heating process of proteins is accompanied by the unfolding of globules and the release of free radicals, which gives rise to the possibility of the formation of intermolecular bonds, aggregation of particles and their precipitation, which leads to a decrease in the solubility of proteins.

The internal rearrangement of the protein molecule - actually denaturation - is manifested in the aggregation of polypeptide chains. The aggregation process proceeds in two stages: coarsening of particle sizes without leaving the solution and subsequent coagulation. Aggregation of denatured protein molecules, or a change in their quaternary structure, which is a consequence of the previous restructuring of the secondary and tertiary structures, is accompanied by a reduction in the lyophilic centers of the protein molecule and a decrease in the water-holding capacity of meat. Aggregation and coagulation of proteins determine the formation of a continuous spatial frame of the finished product.

The rearrangement of the protein molecule during denaturation worsens the hydrophilic and enhances the hydrophobic properties of the tissue, therefore, the protective (stabilizing) effect of hydration layers near the polar groups is weakened. Intramolecular bonds are replaced by intermolecular ones, an insoluble clot is formed, i.e., proteins coagulate (flakes fall out of dilute solutions, and coagulation occurs from concentrated solutions).

The process of protein denaturation is accompanied by the destruction of the water structure, as a result of which the secondary forces acting between the protofibrils (van der Waals forces) give the myosin molecule a more compact shape, while part of the liquid is released.

As a result of denaturation and coagulation of muscle proteins, the strength properties of meat increase, and the welding of collagen and its subsequent hydrolysis, on the contrary, weaken them.

2.2 Change in fat when meat is heated

Heat treatment of meat and meat products causes the destruction of a complex intracellular colloidal system, which contains fat. At the same time, it melts and then coalesces, forming a homogeneous phase in the cell in the form of a drop. If the fat cells were destroyed before the heat treatment or are destroyed during the heating process, the molten fat flows out, merging into a single bulk phase. In cases where heating occurs in an aqueous medium, a small part of the fat forms an emulsion with water.

With a sufficiently long heating with water (including intracellular), fat undergoes significant chemical changes, with moderate heating, they are small, but easily detected. In table. 2 shows the changes in some characteristics of beef tallow that has been heated with water at 100° C. for 1 hour in the presence of a small amount of sodium chloride.

Influence of wet heating of fat on changes in some of its qualitative characteristics

Table 3

Change in the acid number of fat under the influence of high-temperature heating

An increase in the acid number indicates the hydrolytic decomposition of fat, a decrease in the iodine number indicates the saturation of unsaturated bonds of fatty acid radicals, an increase in the acetyl number indicates the addition of hydroxyl groups to fatty acid radicals. Against the background of a decrease in the iodine number, an increase in the acetyl number can be considered evidence of the addition of hydroxyl groups at the site of double bonds as a result of the interaction of triglycerides with water.

If the hydrolysis of fat on a small scale does not lead to a decrease in nutritional value, then the addition of hydroxyl groups to acid radicals is direct evidence of a decrease in the nutritional value of a part of the fat.

Under conditions of humid and prolonged heating at temperatures above 100°C, hydrolytic processes are significantly accelerated, namely, the hydrolysis of triglycerols and the saturation of double bonds of fatty acid radicals with hydroxyl groups (Table 3).

When cooking meat products and bones in a large amount of water at a boil (broths, soups), part of the melted fat is emulsified, being distributed throughout the entire volume of the broth in the form of tiny balls. Emulsified fat gives the broth an unpleasant greasy taste and cloudiness. Fat emulsification is enhanced by increasing hydrolysis and boiling intensity. Periodic removal of fat from the surface of the broth reduces the degree of its emulsification.

When indicated in the table. 3 parameters, the iodine number of fat decreases even more noticeably and the more intense, the higher the temperature. Since the acetyl number increases along with this, there is reason to believe that the formation of hydroxy acids occurs.

Table 4

Changing the properties of beef fat, repeatedly used for frying products

Characteristics of fat		Frying serial number

Acid number
Saponification number
Unsaponifiables
Iodine number
Acetyl number
Reaction to aldehydes	negative	Positive	Positive	Pronounced

Under conditions of dry heating, for example, when frying, oxidative changes in fats and polymerization processes come to the fore. In table. 4 shows some characteristics of beef tallow reused for frying.

An increase in the saponification number indicates the accumulation of low molecular weight acids, and an increase in the acetyl number indicates the formation of hydroxy acids.

In the process of heating, the peroxide number of fat increases and the content of acrolein in fat increases significantly. The color of the fat darkens, the smell deteriorates mainly as a result of the transition of colored products of the pyrogenetic decomposition of organic substances into it. With prolonged use of fat for frying, digestibility decreases as a result of the accumulation of oxidation and polymerization products in it. Heating fat to high temperatures even under vacuum leads to a slight decrease in iodine number and an increase in its viscosity.

Oxidation, polymerization and cyclization are primarily linolenic and linoleic acids. In this case, the formation of six-membered unsaturated cyclic compounds, oxidized polymers and other substances harmful to the body is possible. These processes become noticeable at high heating temperatures, therefore, during frying, the fat temperature should not exceed 170 ° C.

Heating the broth at 100°C for an hour prevents the fat from going rancid. Apparently, this is due to the formation of antioxidants.

During sterilization, fats and their oxidation products interact with proteins, forming complexes - proteolipids and liponroteids. These processes, along with the formation of hydroxy acids, reduce the nutritional value of meat products.

2.3 Modification of extractives

The extractive substances of meat undergo significant changes during its heat treatment, which play a decisive role in the formation of the specific aroma and taste of boiled meat. Thoroughly washed from water-soluble substances, the meat after cooking has a very slight odor, and the water extract from it has the taste and smell of boiled meat. After dialysis, this extract almost loses the smell inherent in boiled meat.

The changes that cause this odor are not yet fully understood. It is known, however, that glutamic acid and degradation products of inosinic acid play an important role in this. Glutamic acid and its sodium salt, even in small amounts (0.03%), give the product a taste close to the taste of meat.

When heated, the decomposition of inosinic acid increases: at 95°C, after 1 hour, about 80% of the acid decomposes with the formation of mainly hypoxanthine. At the same time, the amount of inorganic phosphorus slightly increases as a result of the formation of phosphoric acid.

During the cooking process, the content of other extractives also changes. About 1/3 of the bitter tasting creatine is converted to creatinine. About 10 ... 15% of choline breaks down. As a result of the decomposition of compounds containing labile bound sulfur, hydrogen sulfide is formed in boiled meat, the amount of which depends on the type and condition of the meat, as well as on the cooking conditions. It increases with an increase in temperature and an increase in the duration of heating. In boiled beef, hydrogen sulfide is less than in pork, and it is less than in veal, in frozen meat it is more than in chilled. The release of hydrogen sulfide at moderate temperatures is associated with the breakdown of glutathione (a tripeptide formed by glycine of glutamic acid and cystine), since it occurs when the sulfur of glutathione disappears. Simultaneously with the release of hydrogen sulfide, as a result of the breakdown of glutamine and glutathione, glutamic acid is formed. The introduction of oxidizing agents (nitrite, nitrate) reduces the rate of formation of hydrogen sulfide. When cooking meat, substances are released into the broth, which include carbonyl groups with a different aroma. Acetaldehyde, acetoin, diacetyl were found in the broth. These substances arise due to the reaction of the interaction of free amino acids with reducing sugars (including glucose), which leads to the formation of melanoidins.

During a complex redox reaction, carbonyl compounds are released as by-products.

In the broth obtained by boiling defatted beef, using the chromatographic method, low molecular weight fatty acids (formic, acetic, propionic, butyric, isobutyric), which also have a pronounced aroma, were detected.

It can be assumed that the specificity of the smell of boiled meat is associated with the composition of the lipid fraction of muscle tissue, since the smell of different types of defatted meat differs little.

The question of which substances give the meat its specific aroma and taste after heat treatment has not yet been fully resolved. However, the connection between the taste of meat and the content of free purines in it, in particular hypoxanthine, has been experimentally proven. The amount of these substances in muscle tissue is different and depends on the depth of development of post-mortem changes in the tissues. The smell of the broth also has ketobutyric acid.

2.4 Vitamin changes

Heat treatment of animal products at moderate temperatures (up to 100 ° C) reduces the content of some vitamins in them due to chemical changes, but mainly as a result of losses to the external environment. Depending on the method and conditions of heat treatment, the meat loses,%: thiamine 30...60, pantothenic acid and riboflavin 15...30, nicotinic acid 10...35, pyridoxine 30...60, part of ascorbic acid. When cooking products in the shell, the loss of vitamins is somewhat less. So, during steam cooking, 25 ... 26% of thiamine and 10 ... 20% of riboflavin are lost, and when cooked in water, 10% of thiamine and 14% of riboflavin are lost.

Thus, heat treatment of products of animal origin, even at moderate temperatures, leads to some decrease in their vitamin value. Heating at temperatures above 100°C causes various degrees of destruction of many vitamins contained in meat.

Table 5

Heating temperature, 0 С	Heating time, min	Thiamine (B 1)	Riboflavin (B 2)	A nicotinic acid	Pantothenic acid

The degree of destruction depends on the nature of vitamins, temperature and duration of heating. In table. 5 shows the results of the change in vitamins during the heating of pork, depending on the temperature and duration of heating.

Ascorbic acid (vitamin C) is also destroyed and the more, the higher the temperature and the longer the heating. Of the fat-soluble vitamins, vitamin D is the least stable and begins to break down at temperatures above 100°C. The content of vitamin A in the absence of oxygen changes little when heated up to 130°C. Vitamins E and K are the most resistant to heat.

Dry heating in contact with air, for example, when frying meat products, causes an even more intense destruction of vitamins, especially those that are easily oxidized (vitamins A, E, C).

2.5 Change in water holding capacity

Water is a natural component of meat, forming stable structured systems with its other parts. The forms and strength of the water bond in these systems affect the properties of meat, including water-retaining capacity, by the nature of the change in which one can judge the change in weight loss during heat treatment and the quality of the product. At present, the water-retaining capacity of meat is understood as the force with which part of its own water or its own with a small amount of added water is retained by proteins, as well as other substances and structural systems of meat, when any external forces act on it.

Many factors influence the change in the water-retaining capacity of meat during its heat treatment: the temperature to which it is heated, the duration of exposure at it, the temperature of the environment, the method of heat treatment, the heating rate, the pH value of the processed raw materials, rheological characteristics, the chemical composition of the product, the amount of added salt, water, type of meat, anatomical origin of muscles, age of animals, etc.

Most researchers attribute the decrease in water-binding capacity and loss of moisture in the process of heating meat only with a change in the conformational structure of the protein.

Changes in the proteins of muscle and connective tissues during heating lead to shrinkage and a decrease in the volume of meat and meat products with an intact structure, which is associated with the release of water. The amount of moisture loss by the product affects not only the hardness, but also determines the yield of the product.

Water losses are significantly affected by the degree of development of coagulation phenomena, which are accompanied by a decrease in water-binding capacity.

Studies of the dependence of the decrease in moisture content on temperature and pH of the minced meat sample showed that the separation of moisture begins already at a temperature of 35°C. However, starting from temperatures of 45...50°C, moisture is released more intensively. This is explained, on the one hand, by the change in the structure of water at the indicated temperatures, and, on the other hand, by the conformation of the protein macromolecule, which is due to a complex of intra- and intermolecular hydrogen bonds and hydrophobic interactions.

Since heating is accompanied by the destruction of water structures (hydrogen bonds and hydrophobic interactions), secondary van der Waals forces acting between protofibrils pull the protein molecule into a more compact form, i.e. polymerization of discrete proteins and an increase in their molecular weight occur. At the same time, with an increase in temperature, the contact of water with a hydrocarbon leads to an energetically less favorable replacement of the water-water interaction by the carbon-water interaction, the protein structure becomes denser, which causes a significant release of moisture in the form of broth.

The most important thing in reducing moisture loss is the choice of such heat treatment regimes, which should be only the minimum necessary according to the characteristics of the composition and properties of the product. This is due to the fact that an increase in temperature in the range of 75-90 ° C by 1 ° C causes an increase in weight loss by an average of 0.37% versus 0.25% when heated from 65 to 75 ° C and 0.14% - when heated from 55 to 65°C

The water-binding capacity of meat products subjected to heat treatment can be increased by using fresh or well-ripened meat, as well as by shifting the pH in one direction or another from the isoelectric point of proteins (phosphates, organic acids). Table salt in relatively small amounts increases the water-binding capacity, in large quantities it decreases.

In addition to changes in the structure of water, denaturation changes in muscle proteins and collagen disaggregation, the pH of raw materials has a significant impact on the change in water-holding capacity.

The change in pH during meat heating is more strongly influenced than the temperature of the heating medium by the pH of the feedstock and the temperature of the sample. Despite the fact that with an increase in the latter, the increase in pH increases (the amount of increase depends on the pH of the original minced meat), its water-retaining capacity decreases, since in parallel the isoelectric point of fibrillar proteins shifts to higher pH values.

physical chemical biological thermal meat

3. Color formation

During heat treatment of muscle tissue, changes in myoglobin are very important, on which the color of meat depends: at 60 0 C, the red color remains inside the meat, at 60-70 0 C, corresponding to the temperature of myoglobin denaturation, the emulsion is intensively stained pink. As a result of denaturation, the color of myoglobin is lost, it becomes insoluble.

It should be noted that the higher the heating temperature, the less stable the color of meat products. Exceeding the regulatory level of the final temperature in the center of the product during cooking (up to 75-80 0 C) leads to a change in the color of the meat and a gray-brown hue.

With nitric oxide, myoglobin forms a compound whose color (red) does not change when heated. This explains the stable color of corned beef, sausages, sausages, because saltpeter is added to the salted mixture.

4. Formation of taste and smell

Glutamic acid plays an important role in the formation of the taste of boiled meat. Its appearance during thermal exposure to meat is possible as a result of the release of amino acids from proteins and the deamination of glutamine, which is located in muscle tissue.

An important role in the formation of aroma and partly the taste of meat when heated is played by the reaction of melanoidin formation, or the Maillard reaction. This is an interaction reaction between the amino groups of free amino acids, polypeptides or proteins and the carboxyl groups of carbohydrates.

The Maillard reaction is a series of reactions resulting in the formation of intermediate products that cause the appearance of a characteristic odor - carbonyl compounds (aldehydes, ketones, volatile acids), sulfur-containing compounds, etc. The end products of these reactions are melanoidins - dark brown polymers (Fig. 2).

Rice. 2. Scheme of melanoidin formation

Under normal conditions, this reaction proceeds very slowly, its consequences affect only during long-term storage. Heating dramatically accelerates its flow. The intensity of the formation of melanoidins and their intermediate products depends on the temperature and duration of exposure to heat. Therefore, in the most obvious form, the consequences of this reaction are manifested during sterilization, baking and frying.

From consumer, technological and biomedical points of view, the impact of melanoidins on food products is ambiguous. They have a positive effect on flavor at moderate heating temperatures and have a negative effect on color, causing browning of canned and fried foods. Melanoidins, formed during the culinary processing of products, are not broken down by human digestive enzymes.

Sulfur-containing amino acids, which are part of the protein, release hydrogen sulfide during destruction, and other compounds are formed - mercaptans. Sulfur-containing compounds play a leading role in the formation of the smell of boiled meat. Thus, more than 25 sulfur-containing substances were found in the volatile components of boiled meat. During heat treatment of meat, phosphatides and phosphoproteins break down during destruction to form phosphine (PH 3). Also, heating the meat is associated with the melting of fat and its partial emulsification. Simultaneously with the melting of fat, some volatile compounds are released, giving flavor to meat and broth. The composition of high-molecular compounds of the boiled product also includes volatile low-molecular fatty acids (formic, acetic, propionic, butyric, etc.).

The nature of the formation of flavoring substances of meat, as well as their losses during heat treatment, significantly depend on the type of product, its structure, method and technique of heating, on the presence or absence of a protective shell on the surface of the product. It has been established that the milder the heat treatment modes, the more pronounced the meat flavor of the finished products.

5. Organoleptic indicators

As a result of heat treatment, meat acquires new characteristic taste, aromatic qualities, a dense texture, becomes more stable during storage and is usually better absorbed. In this case, there is a change in its biological value.

It is heating that causes changes in the constituent parts of meat responsible for the appearance of meat taste and aroma. Extractive substances play a decisive role in the formation of the taste and smell of boiled meat. Quantitative changes in many extractive substances are due to two oppositely directed processes: their accumulation as a result of the decomposition of macromolecular compounds and a decrease due to their own decomposition under the influence of heating and losses to the environment.

The loss of water-soluble proteins and extractives during cooking determines the taste and aroma of the broth. When meat is immersed in cold water, the mass fraction of these substances is much higher than when immersed in boiling water. In the latter case, there is a rapid coagulation of proteins in the surface layer. Therefore, in sausage production, products are immersed in boiling or heated to 95 ° C water.

Conclusion

The nutritional and biological value of meat and meat products is determined by a number of both positive and negative aspects. Meat proteins after heat treatment become more accessible to the action of digestive enzymes, which is especially important for collagen. Therefore, heating increases the level of their digestibility and digestibility. At the same time, prolonged heating can increase the resistance of proteins to enzymes due to the development of post-denaturation changes. This is typical for sterilized meat.

Heating causes inactivation and destruction of vitamins, especially water-soluble ones. As a result of the release of moisture, some of the water-soluble proteins, amino acids, extractives, and fatty acids are lost. Maillard reaction products are difficult to digest in the body and can provoke carcinogenicity.

During the heat treatment of meat and meat products, a number of biochemical, physicochemical and microbiological processes occur, as a result of which the hygienic safety of products, their culinary readiness is ensured, organoleptic properties are formed, and storage stability increases. The principal direction of these phenomena is preserved for all types of heat treatment. At the same time, due to the specifics of the technologies of certain types of meat products, each of them has its own distinctive features.

Literature

1. Technology of catering products. In two volumes. Volume 1. Physical and chemical processes occurring in food products during their culinary processing; A.S., Ratushny, V.I. Khlebnikov, B.A. Baranov; Mir Publishing House, 2003

2. D.V. Ketselashvili, Technology of meat and meat products, part 2; Kemerovo Institute of Technology Food Industry; 2004

3. L.G. Vinnikova, Technology of meat and meat products; «Firm «Inkos» 2006

4. Biryukova V.V., N.V. Shevchenko Technology of production of public catering products; Omsk State Technical University 2004

5. Nechaev A.P., Traubenberg S.E., Food chemistry, 2003

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1 Types of heat treatment of meat

It is difficult to list all the cooking methods - there are too many of them. But there are several main ones, and these are:
1. Boiling carried out in water or steam. When cooking meat, various vegetables and seasonings are added to enhance the taste.
2. Frying. Everyone loves fried foods except nutritionists. Let's see why below.
3. Baking. It can be produced both in foil, plant leaves, and in special dishes.
4. Stewing - in most of its options, the most time-consuming heat treatment of meat. Stewing meat, in addition, certain skills.
5. Grill. These are kebabs, adored by many, and grilled chicken, and shawarma - everything that is cooked on an open fire. Unfortunately, for the vast majority, this method cannot be everyday.
The heat treatment of meat by each of these methods leads to certain changes in the structure and composition of the meat. Which, of course, is reflected in the usefulness of the final products.

2 Classification of thermal equipment

Surface methods of cooking food products for technological purposes are classified into cooking, frying, frying-baking, water-heating and auxiliary.
Cooking equipment includes:
cooking kettles, the technological medium of which is water or broth at a temperature of 100 ° C;
autoclaves in which heat treatment is carried out with steam at a temperature of 135 ... 140 ° C;
steamers, in which the technological process of cooking is carried out with steam at a temperature of 105 ... 107 ° C;
vacuum apparatus, the working medium of which is heating steam at a temperature of 140 ... 150 ° C.
The group of frying equipment includes:
frying pans in which the frying operation is carried out in a small amount of fat at a temperature of 180 ... 190 ° C;
fryers, the frying process in which takes place in fat at a temperature of 160 ... 190 ° C;
ovens (grills, barbecue ovens) that carry out the process of cooking products in hot air at a temperature of 150 ... 300 ° C.
The frying and baking equipment includes: ovens, ovens and baking cabinets, in which the technological medium is hot air at a temperature of 150 ... 300 ° C;
steam fryers, the working medium of which is a mixture of hot air and superheated steam at a temperature of 150 ... 300 ° C.
Water heating equipment is represented by boilers and water heaters.
Auxiliary equipment includes food warmers, heating cabinets and racks, thermostats, equipment for transporting food.
Volumetric methods of heat treatment of products are carried out: in microwave cabinets of periodic and continuous action; microwave method provides a high heating rate of products;
IR devices; infrared heating is based on the intense absorption of infrared radiation by free water in the products;
EC-heating devices; electrocontact heating is based on the thermal energy released by the current for a certain time when it passes through a product with a certain active (ohmic) electrical resistance;
induction heating installations; induction heating of food products, especially with high humidity, occurs when they are placed in an external alternating magnetic field, in which, according to the law of electromagnetic induction, eddy currents (Foucault currents) occur, the lines of which are closed in the thickness of the product, electromagnetic energy is dissipated in its volume, causing heating .
The main advantage of the microwave is the speed of heating food products.
However, this method of heating also has disadvantages - the absence of a crust on the surface of the product and, as a rule, the natural color of the raw material.
Positive indicators of IR heating are uniform color and thickness of toasting.
However, this method has disadvantages:
not all products can be subjected to IR heating;
at a high flux density of IR radiation, a “burn” of the product is possible.
EC heating is used as an independent type of treatment, and in combination with other methods. In particular, it is successfully used in the bakery industry to warm up the dough mass when baking bread, in the production of sausages, and in blanching meat products.
The induction heating method is not yet widely used in catering, but it has significant economic opportunities for successful use in the future.
Taking into account the fact that surface and volumetric methods of heat treatment of food products, along with advantages, also have disadvantages, it is advisable to use them in combination in the production of public catering.

3 Preliminary heat treatment of raw meat

Raw materials are sometimes subjected to preliminary heat treatment before being placed in a jar: blanching, roasting, boiling, roasting, smoking.
Blanching. It is a short-term cooking of the product in water or in its own juice until incompletely cooked. The purpose of blanching is to reduce the water content of the meat so that there is a higher concentration of nutrients in the jar (the mass of meat after blanching is reduced by 40-45%). In the process of blanching, the connective tissue is partially boiled, its strength decreases. Blanching also has a detrimental effect on the vegetative microflora found in the meat and contributes to the efficiency of sterilization. As a result of blanching, the meat is reduced in volume by 25-30%, which allows the maximum use of the container capacity when packing canned food. There are several ways to blanch meat.
In the first method, trimmed meat is placed in a blancher (or cauldron) with boiling water in a ratio of 53: 47. To obtain the broth of the required concentration, three pieces of meat are blanched in one cauldron. The first bookmark is blanched for 50-60 minutes, the second - 1 hour 15 minutes and the third - 1 hour 30 minutes. The fourth bookmark in the same broth should not be carried out, since the duration of cooking increases, and the density of the broth almost does not change, in addition, the quality of the broth and meat deteriorates.
In the second method - blanching meat in its own juice - the meat is loaded into the blancher by 2/3 of the volume, adding hot water - 4-6% of the mass of meat. After a single blanching for 30-40 minutes, the broth is sufficiently concentrated, suitable for direct use in canned food without additional evaporation.
In the third method, 15-20% water is added to the meat, blanching continues for 30-40 minutes. Then the meat is unloaded, and the remaining broth is evaporated. After blanching the second batch, the meat is also unloaded, and the resulting broth is suitable for adding to canned food in terms of concentration.
Blanching is considered complete if the meat on the cut is gray and does not release bloody meat juice when pressed.
For canned food "Beef tongue in its own juice", as well as for some offal canned food, blanching is allowed to be excluded. In this case, when packing, instead of the broth, dry gelatin is placed in the jar. As a result, the duration of the technological process is reduced, raw materials are saved. In the manufacture of some types of canned food, vegetable fillers are also blanched. In particular, frozen green peas and rice are blanched for 5 minutes.
Raw materials are blanched in machines and apparatuses of periodic and continuous action.
Intermittent devices include a tilting digester designed for cooking and blanching meat and offal, preparing sauces and broths, and frying meat.
It consists of two cavities: an open one, into which the heated product is placed, and a hermetically sealed steam jacket. The working steam pressure in the jacket is 1.5-6.0-105 Pa. From above the copper has a removable cover; at the bottom is a condensate drain valve. When the steering wheel 4 moves, the digester rotates on hollow trunnions 5 and unloads after the end of the heat treatment.
For blanching and cooking meat and meat products, Vulkan boilers are also used. The boiler consists of two cylindrical tanks with spherical bottoms inserted one into the other and forming a steam engine. Both reservoirs 2 are connected around the circumference with bolts, which ensure tightness due to the presence of a gasket between the flanges. The boiler has a hinged lid / with a counterweight, which is fixed during operation of the boiler with cap screws. The boiler is equipped with a pipe 4 for draining condensate and a pressure gauge 5. The meat is loaded into the boiler in baskets with or without a hoist. The water temperature is 80-100°C.

3 Cooking equipment

The main technological requirements for the design of cooking apparatuses are reduced to obtaining a high-quality finished product with maximum preservation of proteins, fats, carbohydrates, vitamins, minerals and extractives with minimal heat consumption.
Digestion boilers are used to obtain a finished product with high organoleptic qualities with the maximum preservation of substances in the feedstock and its biological value. In order to meet these requirements, the design of food boilers should provide: heating of the product not higher than 100°C with regulation of the cooking mode within the boiling temperature; turning off the heating before the end of cooking.
Vacuum apparatus should ensure maximum preservation of the natural structure of the product, coloring matter, vitamins, minerals and nutrients while increasing the concentration of the original product.
The heating of the product and the implementation of the process of cooking (evaporation) in a vacuum apparatus must take place at a temperature below 100°C.
Digestion cabinets are used to maximize the preservation of food and biological substances in the product for the minimum period of its preparation. The main technological requirement for the design of these devices is the impact of wet saturated steam at a temperature of 105 ... 107 ° C without access to atmospheric oxygen.
Autoclaves at catering establishments are mainly used for cooking bone broths for maximum extraction of nutrients (proteins, fats, minerals, extractives). Their design should provide heating of the product at temperatures not exceeding 130 ... 135 ° C for 1.5 ... 2.5 hours without access to atmospheric oxygen and the possibility of removing fat during the cooking of broths.
Cooking equipment, depending on the pressure in the cooking vessel, is classified into digesters operating at atmospheric or slight excess pressure, and autoclaves operating at elevated pressure (250 kPa).
Depending on the source of heat, boilers are divided into solid fuel, gas, electric and steam. The method of heating can be direct and indirect.
Boilers with direct heating can operate on solid fuel, gas and electric heating. They are simpler in design and operation than boilers with indirect heating, but they have a number of significant drawbacks: low efficiency, difficulty in regulating the thermal regime, and the possibility of burning products.
Boilers with indirect heating operate at increased pressure in the heating jacket up to 150 kPa. Water is used as an intermediate heat carrier.
According to the installation method, boilers can be non-tilting, tilting and with a removable cooking vessel. As a rule, non-tilting boilers are produced with a capacity of more than 100 dm 3 of the digester, and tilting boilers - with a capacity of less than 100 dm 3. Boilers with a removable cooking vessel have a capacity of less than 60 dm 3 .
Digestion kettles have an alphanumeric index. The numbers show the capacity of the brewing vessel in dm3; letters indicate the group, type of boiler and energy carrier. For example, the KPESM-60 index is deciphered as follows: electric sectional modulated digester boiler with a capacity of 60 dm 3; the index of the device with a removable cooking vessel UEV-60 is deciphered as follows: electric device with a capacity of 60 dm 3 .
Boilers operating at elevated pressure in the digester have an index in which the first letter A indicates that this is an autoclave, the second letter indicates the type of energy carrier (E - electric, G - gas), and the number shows the capacity of the digester in dm 3, for example AE-60.
The digester is a vessel with a lid. Outside, the boiler is covered with a layer of thermal insulation laid between the lining and the boiler body. A steam generator combined with a steam jacket is mounted in the lower part of the boiler. The design of the boiler is installed on a pedestal. The steam generated in the steam generator fills the steam jacket, in contact with the cooking vessel, condenses, transfers the heat of vaporization to the wall, along which the condensate flows back into the steam generator.
Digestion boilers with indirect heating are equipped with instrumentation and safety fittings. These include:
pressure gauge for measuring the pressure in the steam jacket during operation;
level cock to control the amount of water in the steam generator;
a filling funnel designed to fill the steam generator with water and release air from the steam-water jacket during the initial period of boiler operation;
purge cock installed in conjunction with a steam trap;
used to release air from the steam jacket, drain condensate before starting the boiler, as well as to check the health of the steam trap;
double safety valve, consisting of two valves - steam and vacuum, located in a common housing; when the pressure in the heating jacket rises above the permissible value (150 kPa), steam, overcoming the mass of the load, lifts the valve above the seat and begins to escape into the atmosphere; the vacuum valve is opened by outside air pressure when a vacuum is formed in the jacket;
turbine valve on the lid of non-tilting boilers; it protects the brew vessel from pressure buildup above 2.5 kPa.
On fig. the structural scheme of the boiler gas digester tilting KPG-60M is given.

Rice. Tilting gas digester boiler KPG-60M: 1 - cooking vessel; 2- outdoor boiler; 3- thermal insulation; 4- steam-water jacket; 5 - steam generator; 6 - flange; 7 - pedestal; 8 - injection burner; 9 - rotary wounds; 10 - manometer; 11 - filling funnel; 12- level tap; 13- door; 14 - gas automation unit
The boiler is installed on a cast iron fork-shaped frame with the help of trunnions, which ensure the overturning of the boiler by a worm gear.
The steam generator of the boiler consists of two pocket cylinders inserted one into the other. The inner pocket forms a combustion chamber, the outer pocket forms an annular gas duct. A gas injection burner is installed in the gas burner chamber.
Primary air is supplied to the burner by a primary air regulator, which is made in the form of a washer moving along the threaded thread of the pipe with a nozzle. Secondary air enters the burners through the annular gap at the base of the boiler. The products of combustion from the combustion chamber are removed by the chimney.
To ensure the safety of operation, the boiler is equipped with a double safety valve, a water level cock, a filling funnel, gas automatic safety and regulation type 2 ARB.
On fig. shows a diagram of a digester gas sectional modulated boiler KPGSM-60.

Rice. Sectional modulated digester gas boiler KPGSM-60: 1- chimney; 2- outer case; 3 - cooking vessel; 4 - reinforcing unit; 5- cover; 6- level tap; 7- handwheel; 8-door; 9-legs, adjustable in height; 10 - frame; 11 - branch pipe; 12 - casing; 13 - burner; 14 - firebox; 15 - annular gas ducts; 16 - steam generator; 17 - outer lining of the boiler
Its main structural elements are a cooking vessel, a low-capacity steam generator and an outer casing with a heat-insulating coating.
The steam generator is made in the form of two cylindrical pockets of different heights, the outer walls of which form a furnace and two annular gas ducts. A burner with an annular nozzle and an igniter is installed under the furnace in a special cylindrical casing. There are special holes in the bottom of the combustion chamber for suction of secondary air.
A tilting device and a supply gas pipeline are mounted in the right column of the boiler. Hot and cold water pipes are located in the left column.
The boiler is equipped with the same safety features as the KPG-60M boiler.
Steam cooking boilers have a similar design as gas boilers. They differ in that the steam that heats the cooking vessel is not formed in the boiler itself, but enters the steam jacket from the outside through the steam pipeline. The heating of the cooking vessel is carried out due to the heat of vaporization. Steam, getting into the jacket of the boiler, comes into contact with the cold walls of the cooking vessel and the outer casing. It condenses with the release of the latent heat of vaporization, which is used to heat the contents of the boiler with a high heat transfer coefficient. Centralized preparation of steam as a heat carrier increases the performance of the boiler due to the fact that its design in this case does not provide for the installation of a steam generator.
At public catering establishments, steam boilers KPP-100, KPP-160 and KPP-250 are used. They have the same design and differ only in the size of the working vessel.
Non-tilting electric kettles KPE-100, KPE-250, KE-100, KE-160, KE-250 and tilting KPE-40, KPE-60, KPESM-60, as well as devices with a removable cooking vessel UEV-40, UEV-60.
The design diagram of the KPE-100 digester is shown in fig.

Rice. Electric food boiler KPE-100: I - cladding; 2 - thermal insulation; 3 - trial valve; 4 - sensor; 5 - heaters; b - steam generator; 7 - pressure switch; 8 - pressure gauge; 9 - rotary crane; 10 - cover; 11 - turbine valve; 12 - turbine valve reflector; 13 - gasket; 14 - overhead levers; 15 - funnel; 16- double safety valve; / 7-station control; 18 - handle; 19 - lamp "On"; 20 - lamp "No water"; 21 - counterweight; 22 - cold water pipeline; 23 - drain cock; 24 - filter
The boiler is permanently mounted on a pedestal. In the steam generator, located under the bottom of the boiler body, six heating elements are mounted. The boiler is hermetically sealed with a double-walled lid, balanced by a counterweight, which allows it to be fixed in any position.
The boiler is equipped with an automatic control of the thermal regime, an electrocontact pressure gauge, a double safety valve, a turbine valve, a light alarm and a control station. In addition, protection of the heating elements against "dry" running is provided, which prevents the boiler from turning on when the heating elements are not completely covered with water, and also disconnects the boiler from the electrical network when the water level in the steam-water jacket drops below the permissible level. In both cases, a light alarm is triggered.
The boiler operates in two modes. The first mode provides automatic disconnection of five heating elements from the network at the maximum allowable pressure and their inclusion after the pressure drops to the lower limit; the second mode automatically disconnects all heating elements from the network after the specified pressure is established in the steam jacket.
KPESM-60M electric sectional modulated digester boiler is a tilting cooking vessel with a steam-water jacket.
To supply water to the brew vessel, a water pipe with a mixer at the bottom and a filling tube at the top is attached to the inside of the right cabinet. To control the mode of operation of the boiler, signal lamps are used: for the "Strong" mode - green; "Weak" - yellow; "No water" - red. The water level in the steam-water jacket is checked using a drain cock. Safety valves are used to regulate the pressure in the steam-water jacket.
The operation of the boiler is as follows. The heaters heat the water in the steam-water jacket to a boil, the resulting steam fills the space of the steam-water jacket and displaces air from it, which exits through the air valve. After the air valve is closed, the pressure in the steam-water jacket begins to rise to the upper specified limit. If the pressure is above 0.05 MPa (0.5 atm), the electrocontact pressure gauge (EKM) will disconnect the heaters from the mains or switch the circuit to low heating. In the event of a malfunction of the EKM, the safety valve is activated.
On fig. a schematic diagram of the construction of a spherical batch vacuum apparatus is given.

Rice. Spherical vacuum apparatus: 1 - copper bowl; 2- steam jacket; 3-crane for air purge; 4 - gear transmission; 5- mixture suction fitting; b- copper cap; 7- thermometer; 8- union nut; 9 - pipeline; 10 - branch pipe; 11 - vacuum gauge; 12 - tap for sampling; 13 - manometer; 14- safety valve; 15 - electric motor; 16 - steam valve; 17 - mixer; 18 - shutter; 19 - valve for condensate; 20 - air valve; 21 - viewing window; 22 - gearbox
The vacuum in the working area (bowl) helps to reduce the boiling temperature of the product.
The vacuum apparatus is a non-tilting double-walled digester, inside of which a stirrer is mounted. The bowl is placed in a steel steam jacket, on which, on the right side, there is a steam pipe with a valve, a pressure gauge and a safety valve. On the left side of the steam jacket, there is an air cock for purging the steam space and a valve for connecting a steam trap.
The boiler bowl is closed with a cap, on which a thermometer, a vacuum gauge and an air cock with a funnel are mounted. The cap ends with a branch pipe for connecting the pipeline. There is a baffle inside the hood to prevent product carryover into the vacuum line.
The pipeline connects the vacuum apparatus with the condenser of the wet-air piston vacuum pump to create and maintain a vacuum in the vacuum apparatus.
The vacuum apparatus is loaded with the product through a fitting, which is sucked in with a vacuum pump and a flexible hose into the working area. For unloading, the lower drain fitting with a shutter is used. A special crane was installed for sampling. The process of loading and boiling the product is observed through viewing windows.
The agitator is driven by an electric motor through a worm gear and a pair of gear wheels. The agitator shaft has a stuffing box seal.
For cooking filling soups, second and third courses, side dishes, stewing vegetables, as well as transporting ready meals to the distribution line and keeping them hot, electric cooking devices UEV-60 and UEV-40 are used.
The cooking device is a mobile boiler with a steam generator.
The steam generator has three heating elements, a dry-running protection sensor, a filling funnel, a pressure gauge, a safety valve, and a knob for the mode switch of the brewing device.
Guides are welded to the steam generator, along which the boiler is moved to dock it with the steam generator using a lever steam locking device.
The preparation of medical, baby and dietary food, when it is required to preserve the nutritional value of raw materials as much as possible, is carried out on a “hot” steam. With this method of heat treatment, saturated steam, in direct contact with the products, condenses and gives them the heat of vaporization.
For steaming meat, fish, vegetables, as well as for heating various culinary products, steamers of domestic production APESM-1, APESM-2, APE-023A, APE-023A-01 are used.
The figure shows the structural diagram of the APESM-2 steamer.

Rice. Steamer APESM-2: 1 - valve on the drain pipeline; 2-heating elements; 3- steam generator; 4 - legs; 5-camera door; 6 - valve on the steam generator; 7 - lock; 8 - base; 9 - control panel; 10 - ground bolt; 11 - casing of the terminal block of heating elements; 12 - nutrient tank; 13 - sensor of the automatic system of protection against "dry running"; 14 - steam pipeline; 15 - perforated stewpan; 16 - removable square for installing dishes; 17 - cooking chamber; 18 - non-perforated stewpan; 19 - cap (top cover); 20 - pipeline for draining condensate into the sewer; 21 - signal lamps; 22 - switch; 23 - switch
The principle of operation of the device is based on direct heating of the contents of the cooking chambers with steam at atmospheric pressure, which is formed when water is heated in the steam generator by tubular electric heaters and.
If the pressure in the water supply network is normal, the coils of the magnetic starters turn on. When the contacts are closed, the magnetic starters become self-powered. At the same time, the heaters are connected to the network and the light signaling "Heating" is turned on. The steamer enters the stationary mode of operation after 20 minutes.
Protection of steam generator heaters from "dry running" is carried out using a sensor that is triggered when the water pressure in the water supply network drops below 0.05 MPa (0.5 atm).
Autoclaves are not widely used in public catering establishments, as they require long-term heat treatment of food raw materials. They are used for cooking meat and bone raw materials to obtain certain types of culinary products (broths, aspics, etc.).
The autoclave is a cooking vessel enclosed in a heat-insulated steel case. At the bottom of the steam jacket there is a steam generator with three heating elements with a total capacity of 10.8 kW, which heat water to the boiling point and turn it into steam.
The autoclave is equipped with instrumentation and safety fittings, pipelines for hot and cold water supply, automatic control of the thermal regime and protection of heating elements from "dry running".
In the process of heat treatment of food products, a pressure of up to 320 kPa (3.2 atm) is created in the cooking vessel. To release air at the beginning of cooking and high-pressure steam at the end of it, a purge valve is provided on the autoclave lid.
The brewing equipment includes coffee makers. In batch coffee makers, the drink is obtained by repeatedly circulating boiling water at atmospheric pressure through a sieve filled with ground coffee. In express coffee makers, a filtration method is used, in which boiling water is passed through a layer of coffee at elevated pressure. In this case, the extraction of aromatic extractive substances occurs.
The force that pushes the water through the coffee bed is either created by the pressure of the steam generated in the kettle or by a manually or hydraulically driven piston.
On fig. shows a diagram of an express coffee maker with hydraulic force.

Rice. Schematic diagram of the express coffee maker:
1 - block edge; 2 - thermometer scale; 3 - sensitive element of the thermometer; 4,10,16 - valves; 5- hot water boiler; b - safety valve; 7- manometer; 8 - coil; 9 - water gauge glass; 11 collector; 12 - steam nozzle; 13 - bowl-holder; 14 - water softener; 15 - cold water supply line; 17 - heater; 18 - sleeve for the selection of hot water; 19 - condensate drain line
The water used to prepare the drink enters the coil located in the hot water boiler connected to the water supply network by a float valve, heats up there and is fed through the distribution manifold to the block valves with push-button control and a hydraulic booster.
The boiler is equipped with a safety valve and thermostat.
The block valve opens the passage for water from the coil and due to the pressure under which the water is in the coil, it passes through the layer of ground coffee. The finished drink is poured into a cup placed under the horn of the block tap head.
To maintain the required water pressure (at least 250 kPa), it is pumped through a hydraulic booster from the water supply unit. The pump pumps water into the tank until the pressure in it and the associated coil rises to the required value.
Public catering establishments use express coffee makers of various types of domestic and foreign production, differing mainly in design and control system, but working according to the described principle.

CONCLUSION

Depending on the purpose, the nature and mode of heat treatment can be different: surface heat treatment; scalding, singeing, roasting; heating to prevent microbial spoilage of the product; pasteurization, sterilization; heating to the full depth; blanching, boiling, baking, frying; heating to isolate one or another of its constituent parts from the raw material - smelting fat, boiling out gelatin and glue.
The qualitative changes caused by heating are basically similar. Heating methods are different: water, steam, hot air, alternating electric current, in contact or without contact with the heating medium. Since water is the predominant component of meat products, in all cases, heating occurs under the influence of hot water on the components. Therefore, changes in the product will be associated primarily with the hydrolysis of the constituents and a number of other reactions that occur in the presence of water. One of the main factors that make up these changes is the heating temperature.

Heat treatment technology is undergoing significant changes due to the emergence of new types of casings, smoke preparations, technical innovations and other factors. Nevertheless, technologists, when selecting heat treatment modes, should be guided not only by the recommendations of manufacturers of equipment or packaging materials, but also by theoretical knowledge about the essence and significance of each stage of this process.

Draft is the process of curing molded sausage sticks filled with minced meat before heat treatment. Draft is a preparatory stage of heat treatment, which largely affects the quality of finished sausages. Depending on the type of sausages and purposes, short-term and long-term draft are distinguished. Precipitation is carried out in special chambers at a temperature of 0-2 ° C and a relative humidity of 80-85%. Short-term sediment is intended for boiled (1-3 hours), cooked-smoked and semi-smoked (4-6 hours) sausages.

The goals of short-term draft are as follows:

Reducing the excess internal energy (entropy) that accumulates in the mince emulsion during high-speed cutting;
reducing the consequences of the formation of vapor-gas bubbles and cavitation cavities, which have a negative impact on the process of intermolecular interaction of proteins;
thixotropic restoration of the coagulation structure of minced meat, i.e., restoration of bonds between the constituent parts of minced meat, broken at the time of injection.

Minced meat acquires solidity, in the minced system the proportion of firmly bound water increases, which subsequently improves the consistency, increases juiciness and increases the yield of the finished product;
the development of reactions associated with the stabilization of the minced meat color, which continue during the subsequent frying and cooking; drying of the casing, which favorably affects the quality of roasting sausages.
Therefore, during precipitation, it is necessary to maintain air circulation in the chambers. Despite the fact that after precipitation, the mass of the product decreases due to the evaporation of water (losses are about 0.1%), the yield of boiled sausages that have undergone precipitation after heat treatment can increase by 1.2–1.8%.

At present, due to the widespread use of the process of minced meat vacuuming (during cuttering and stuffing), most enterprises do not produce traditional sediment of molded sausage sticks. Most often, frames with sausage are briefly kept before subsequent frying in uncooled rooms at a temperature of 15–20 ° C for 20–60 minutes. Under these conditions, not only the colloid-chemical and biochemical processes characteristic of the sediment are accelerated, but also the meat is warmed up, which is of great importance. During the heat treatment of minced sausages with an initial temperature below 14 ° C, color formation reactions develop slowly, the color of the finished product is gray or quickly lost after cutting. If the molded loaves are served for heat treatment with a temperature above 20 ° C, then the minced meat can turn sour, porosity and green pigmentation appear.

If the draft parameters (especially temperature) are violated, there is a danger:

Development of microorganisms;
reduction of sodium nitrite to molecular nitrogen and discoloration of minced meat (or the appearance of green spots);
increasing the degree of porosity of the product. To exclude the appearance of these undesirable defects, the process of short-term (warm) upsetting must be carried out under strict technological control.

Long-term draft is intended for raw smoked and dry-cured sausages, its duration is 5-10 days. The purpose of long-term precipitation is: in the thixotropic restoration of the minced meat structure, the development of the process of secondary structure formation; in the development of enzymatic processes (maturation) caused by the activity of microorganisms, the activity of tissue enzymes and the properties of protein substances. At the same time, the consistency, taste, aroma and color of sausages are improved. In the process of precipitation, selective development of microorganisms occurs (the development of putrefactive microflora is suppressed, the number of micrococci and enterococci increases). The activity of proteolytic, lipolytic, mucolytic enzymes increases. During sedimentation, with a general increase in the number of microorganisms, the diversity of their forms decreases. The transformation of the qualitative composition of microorganisms continues at other stages of the technological process: during smoking, color-forming (lactic acid) bacteria develop, and their number increases sharply during drying. With prolonged precipitation, moisture evaporates, i.e. dehydration of minced meat. At the same time, the salt concentration increases (as a result of which the growth of harmful bacteria is suppressed), the process of development of minced meat color formation reactions continues (which is associated with a change in the pH value, the presence of microorganisms), a specific taste and aroma are formed, a change in the morphological elements of cells, hydrolytic decomposition of protein substances is observed, solubility decreases proteins, there is a partial destruction of collagen. As a result of pH changes, the sarcolemma of muscle fibers swells and homogenizes, strong intermolecular bonds appear between the active groups of molecules, leading to aggregation of protein particles and strengthening of the structure. A spatial condensation structure is formed (and hardened during smoking and drying), which causes a change in the structural and mechanical properties of the product.

A favorable direction for the development of these processes can be given by the introduction of starter cultures - bacterial starter cultures - into minced meat. Heat treatment Let's consider step by step one of the most common options for heat treatment, namely the classical heat treatment of sausages in a smoke and vapor permeable (breathable) casing, for example, in natural or protein.

The main purpose of heat treatment of meat products is:

In bringing the product to a state of culinary readiness;
in the suppression of vegetative microflora.

Drying.

The purpose of this stage is to warm up the product, remove moisture from the surface of the loaf. Drying is carried out at a temperature of 50−60 ° C, air humidity 10−20%, air circulation speed of 2 m/s. The course of the process depends to a large extent on humidity, and both too humid and too dry air adversely affect the drying result. So, at humidity φ>25%, the process slows down, the shell acquires a gray tint, in some cases gray spots appear. At φ
Roasting

The purpose of roasting is to tan the shell, change its color, give the product a specific aroma and taste. During frying, weakly bound moisture continues to evaporate through the pores of the shell, however, partial denaturation of the protein and precipitation of smoke substances lead to clogging of the pores, which reduces losses and maintains yield. Roasting is carried out at a temperature in the chamber of 70−90 °С, air humidity φ=(52±5)%, air flow circulation speed of 2 m/s. During the roasting process, after the temperature inside the loaf reaches 30–35 °C, the color formation reaction begins with the transition of metmyoglobin to nitrosohemochromogen. It is recommended to finish the frying process at a temperature inside the loaf no higher than 40-45 ° C, when partial denaturation of the protein in the center of the loaf begins, and immediately proceed to cooking. With a delay in the temperature range of 25-30 ° C, the risk of souring minced meat, the appearance of gray spots on the cut, and a sour smell increases.

During frying, the main mass losses of sausages occur, and therefore it is necessary to control the relative humidity of the air in the chamber, as well as to choose the right duration of this stage, which ensures complete color formation, the necessary intensity and uniformity of surface color, the formation of taste and aroma, but in at the same time minimizing weight loss. The main share of losses occurs in the first phase of roasting, and an increase in the heating temperature by 10 °C increases the evaporation rate by 10–15%. Average roasting losses:

For sausages - 10-12% by weight of raw products;
for boiled-smoked sausages - 4-7%;
for semi-smoked sausages - up to 7%.

When choosing roasting parameters, the degree of permeability of the casing to flue gases must be taken into account. The best smoke permeability is in natural (intestinal) casings, and some artificial casings have barrier properties in relation to smoke, and for products in such casings, instead of smoking, it is advisable to use smoke preparations, adding them to minced meat. Cooking. This stage of heat treatment is designed to bring the product to a state of culinary readiness, as well as to destroy the vegetative microflora. The traditional cooking process is characterized by heating the product until it reaches a temperature of 68-72 ° C in the center. Temperature limits are not generally accepted and vary in some countries. Thus, in the United States, in the production of whole-muscle meat products from raw materials with a controlled QMAFANM level (not higher than 104), it is customary to boil until 54 °C is reached in the center of the product. This temperature provides a pasteurization effect while simultaneously denaturing most of the proteins and at the same time minimizes the loss of biologically valuable substances. In Germany, sausages are most often cooked to a temperature in the center of 70 ° C, considering that exceeding this level of heating significantly impairs the smell and taste of the product. When choosing heating parameters, the composition of the products should be taken into account and, if starch is included in the recipe, cooking to higher temperatures, in particular up to 75 ° C (starch gelatinization temperature). For products containing carrageenan preparations, it is most expedient to heat up to 72 °C in the center.

Physical and chemical changes during cooking

During cooking, thermal denaturation of muscle proteins, collagen welding and disaggregation, changes in the state and properties of fat, structural-mechanical properties and organoleptic characteristics of the product, changes in the total amount and composition of the microflora occur. Effect of cooking on meat proteins. Proteins determine the physical and technological properties of minced meat, the structural and mechanical properties of the finished product, its biological value and yield. As a result of cooking under hard conditions, some amino acids (primarily tryptophan, threonine, methionine, histidine) are partially destroyed. In many ways, the quality of the resulting meat products depends on the nature of the denaturation-coagulation transformations of proteins involved in the formation of the structural matrix of minced meat. There are many proteins in meat, and each type has its own denaturation temperature (see table). Denaturation of muscle proteins begins at 42°C, but most of them (80–90%) denature in the range of 54–60°C. In connection with this circumstance, the formation of a secondary protein skeleton is affected not only by temperature, but also by the speed of cooking. High-intensity heating can be accompanied by almost instantaneous denaturation of proteins, and as a result, the structural matrix is less durable, the amount of immobilized moisture in its cells decreases, and the yield of finished products decreases. The use of various types of stepwise heating modes or Δ-cooking (smooth increase in temperature while maintaining the difference between the temperature in the center of the product and the heating medium) with a temperature in the chamber of not more than 80 ° C ensures the consistent involvement of meat proteins that have undergone conformational changes in the process. the process of forming a coagulation structure, with the formation of a greater number of inter- and intramolecular bonds; at the same time, the finished product acquires elasticity, elasticity, juiciness, and moisture loss is reduced.

Influence of cooking on the state and properties of collagen. Heating is the process of introducing a significant amount of energy into the meat system, therefore, under conditions of increased entropy, a weakening of the primary bonds and loosening of its structure occurs in the collagen molecule. With prolonged moist heating, further disaggregation of collagen occurs to compounds with a lower molecular weight - gelatin, glutin, gelatoses. As a result of these changes, the number of hydrophilic groups in collagen significantly increases and, as a result, VSL increases, gel-forming ability manifests itself, which makes it possible to partially compensate for the loss of VSS in muscle proteins. However, excessive long-term heat treatment of collagen-containing raw materials, as well as commercial preparations of animal proteins, can lead to deeper hydrolysis of collagen fragments, a decrease in their functional and technological properties, and the appearance of jelly pockets in the product structure.

Cooking increases the digestibility of collagen, and to achieve culinary readiness, it is enough to hydrolyze 20–45% of native connective tissue collagen. The residual amount of undigested collagen (14–20%) can be considered as a source of dietary fiber.

It has been established that the replacement of up to 24% of muscle protein with pork skin protein does not cause a significant decrease in the biological value of sausages. Hydrolysis of collagen improves the organoleptic characteristics of the product (increases tenderness), changes the structural and mechanical properties (gives the product solidity and the necessary elasticity when biting). Effect of cooking on fat. At present, the fat of industrial breeds of animals has become more fusible and contains more water (up to 12-14% in the spinal; up to 16-17% in the lateral), so the pieces of bacon used for structural inserts (creating a product pattern) are often separated from the minced bases when cutting the finished product. During cooking, the fat melts, partially oxidizes and hydrolyzes, it is emulsified.

Influence of cooking on biological value and organoleptic indicators. Cooking increases the digestibility and assimilation of the product, but causes loss of vitamins and some amino acids. During cooking, the color is stabilized due to the formation of nitrosohemochromogen. As a result of the hydrolysis of proteins and fats, extractives, aldehydes, ketones, diacetyl, free amino acids and their decay products, volatile fatty acids are formed. In addition, proteins and carbohydrates react with melanoidin formation. Thus, a bouquet of smell and taste of the finished product is formed, depending on the heating temperature and the heat treatment time. The structure of meat tissues is changing: the diameter of muscle fibers decreases by 20–35%, and the thickness of the connective tissue increases by 2–2.5 times. Denatured proteins form a new spatial matrix with elastic properties. Influence of cooking on microflora. During cooking (pasteurization) of meat products and sausages, the death of vegetative and partly spore microflora occurs, as a result of which the safety of the product is ensured, its spoilage is prevented and the shelf life is increased.

So, heating at a temperature of 70 ° C for 5-10 minutes ensures the destruction of up to 95-99% of vegetative microflora (under normal cooking conditions, the total microbial number in finished products reaches 103 CFU / g), but at the same time up to 90% of spore-forming organisms remain viable. microorganisms. For the complete destruction of spores, more severe regimes (over 100 °C) are required, which are not used in traditional heat treatment.

Cooling

The purpose of the stage is to preserve the presentation of the product (color, structure, condition of the shell surface), prevent the development of residual microflora, and reduce weight loss. As a result of cooling, the product becomes stable during subsequent storage.

Depending on the type of heat-removing medium, cooling can be water or air. Water cooling. This method provides a high rate of heat removal, an intensive decrease in temperature, a reduction in mass loss, cleans the surface of the loaves from contamination and prevents the shell from wrinkling. In addition, water cooling reduces the degree of syneresis of the mince system, which reduces the likelihood of edema.

Air cooling. It is carried out for additional cooling of meat products after the stage of water cooling, for drying the casing, improving the presentation and preparing for storage or sale. Influence of the cooling rate on the properties of the product The cooling rate affects the aggregate state of muscle proteins (similar to the heating rate). With rapid cooling of denatured globular proteins, their tertiary structure is not completely restored, while with slow cooling, a more stable spatial matrix is formed, and the molecule is partially renatured (see figure). As a result of slow cooling, the structural and mechanical properties of meat products are improved, the solidity of the structure is formed, the WSS and the yield are preserved, and the likelihood of syneresis is reduced.

However, the use of excessively intense and low-temperature cooling regimes leads to wrinkling of the casings, both natural and polyamide, to syneresis, as well as to an increase in the adhesion of minced meat to the casing. Cooling modes There are no unified, clearly regulated recommendations regarding the speed and duration of cooling of meat products, however, in practice, the following modes are usually used, providing, on the one hand, partial restoration of the structure of the protein matrix after heat treatment, on the other hand, achieving the required organoleptic, structural-mechanical, microbiological indicators finished product:

Stage I: irrigation with water (Т=10÷15 °С) up to a temperature in the center of the product no more than 17−30 °С (optimum temperature − 18−25 °С);
Stage II: air blowing (T=4 °C, φ=95%) for 4–8 hours, until the temperature in the center of the product reaches 8–12 °C;
Stage III: post-cooling during storage at (4 ± 4) °С.

Meat

In human nutrition, meat is one of the main sources of protein and fat. The composition of meat, in addition, includes water, minerals, vitamins (A, D, PP and group B).

The main types of meat include beef (cattle meat), veal, lamb, goat, pork, horse meat, rabbit meat, poultry and game.

Meat is steamed, cooled, chilled and ice cream.

The quality of meat is determined by appearance, smell, color and texture. Benign meat has a pink or red color (depending on its type), a dry surface, an elastic texture (when pressed with a finger, the surface of the meat quickly levels out), fat is white or yellowish, hard (in beef) or soft (in pork), not sticky; the smell is pleasant, characteristic of each type of meat.

Primary meat processing

The primary processing of meat consists in defrosting (if the meat is frozen), washing, cleaning and preparing semi-finished products from it.

The meat is thawed in air at room temperature. When defrosted quickly, it loses a lot of juice and becomes tough, less nutritious and tasty. Do not defrost meat in water, as the nutrients and vitamins contained in the juice pass into the water.

Wash the meat with cold running water, and the places covered with fat with warm water. Particularly contaminated places and adhesives are cut off with a knife.

After washing, the meat is cleaned - excess fat, films, tendons are removed and various semi-finished products are prepared from it.

Preparation of semi-finished products. The meat is cut across the fibers into large portioned or smaller pieces, depending on which dish is prepared from it. Chopped meat is beaten off or rolled out with a special roller (Fig. 12). When beating, the connective tissue is loosened, the thickness of the piece is leveled, which contributes to the uniformity of heat treatment.

To obtain a cutlet mass, the meat is passed through a meat grinder (Fig. 13).

In the food industry and public catering enterprises, meat grinders with an electric drive, meat mixers, cutlet-forming machines, etc. are used for meat processing.

Heat treatment of meat

For the preparation of meat dishes, the same types of heat treatment are used as for the preparation of vegetable and fish dishes.

Cooking meat. Meat is boiled for cooking appetizers, first and second courses. To prepare boiled meat, put it in hot water (1-1.5 liters of water per 1 kg of meat), bring to a boil, reduce heat and cook until tender. The readiness of the meat is determined by piercing the fork. When clear juice is released, the meat is considered ready. Boiled meat should be juicy and soft. It is cut into portions across the fibers.

Roasting meat. The meat is fried in large pieces (rump steak, beef steak, entrecote) and smaller ones (beef stroganoff, shish kebab), as well as in the form of cutlet mass products. Pieces of meat prepared for frying or products from cutlet mass are placed on a frying pan heated with fat and fried until golden brown. Large pieces of meat are brought to readiness in the oven.

Minced meat is used to prepare natural products (without adding bread) - steaks, schnitzels, natural cutlets and with the addition of bread - cutlets, meatballs, zrazy, meatballs. The prepared cutlet mass, in which, in addition to minced meat, bread, milk or water, salt, pepper are added, cut into cutlets, meatballs, meatballs and other products and fried.

Cooking meat dishes

Snacks from meat and meat products

Cold snacks are prepared from gastronomic meat products, boiled and fried beef, offal (liver, bumps, hearts). Jellies, aspic dishes, pates, various cold cuts are prepared from meat and meat products, they are also included in salads, vinaigrettes, etc.

Practical work

Meat salad preparation

Inventory and utensils: pots - 2, a bowl, cutting boards VM, VO and CO, a knife, a carb knife, a spoon, a salad bowl.

Norm of products: boiled beef - 20, boiled potatoes - 50, pickled cucumbers - 40, green salad - 10, egg - 10 (1/4 pc.), greens - 2-3, salt - 2-3, mayonnaise - 35.

Recipe

Meat, potatoes and pickles cut into thin slices, lightly salt and season with mayonnaise. The meat is cut across the grain.

Ready salad lie down in a salad bowl with a slide and decorate with lettuce, egg, sprinkle with herbs.

Progress Report

2. Using the recipe, draw up a work plan (sequence of operations) for preparing meat salad.

3. Answer the questions: 1) What tools are used for curly slicing vegetables? 2) What types of salads can be used as a side dish for meat and fish dishes? 3) What safety rules must be observed when working with a knife?

Meat first courses

Broths, dressing soups and soups are prepared from meat. To prepare the first courses, the meat is poured with cold water and boiled until tender. You can cook meat soup with canned food. Gas stations meat soups can be cooked with vegetables, cereals and pasta.

Meat soups and broths are sprinkled with finely chopped parsley and dill before serving.

Requirements for the quality of cooked soup with canned meat.

1. Vegetables, cereals or pasta should not be overcooked, and the vegetables should retain their cut shape.

2. Taste and smell - characteristic of used canned food and sautéed vegetables.

Practical work

Cooking meat soup

Inventory and utensils: a saucepan, a frying pan, a cutting board - CO, grooved and kitchen knives, a slotted spoon, a table spoon.

Norm of products (for 5 servings): canned "stew" - 1 can (338 g), various vegetables - 500-600: white cabbage - 120, potatoes - 300, carrots - 60, onions - 60, canned green peas - 45, salt - 15, parsley or dill, water - 1.5-2 liters.

Recipe

Boil vegetable soup (see recipe on page 28). Saute vegetables for soup on fat removed from canned meat.

Put canned food into the cooked soup and let it boil. When serving, put finely chopped greens in a bowl with soup.

Progress Report

1. Determine the quality of the cooked dish.

2. Answer the questions: 1) What canned meat can be used for making soups? 2) What groups of soups do you know and to which group does the soup you prepared belong? 3) Tell us about the sequence of cooking vegetable soup.

Meat second courses

For the preparation of second courses, boiled and fried meat, as well as products from cutlet mass, are used. Boiled, stewed and fried vegetables, cereals and pasta. In addition to meat dishes, you can serve fresh, salted or pickled vegetables, vegetable salads. When serving, meat dishes are poured with white, tomato or sour cream sauce and sprinkled with finely chopped herbs.

For the preparation of second courses, canned meat is also used: “boiled beef”, “stewed beef”, “stewed pork”, “stewed lamb”, etc. Put the canned food out of the tank into a saucepan or frying pan and bring to a boil. Fat and broth are used to make the sauce. Onion and roots can also be sautéed on fat. Canned stew is served with vegetable and cereal side dishes.

Requirements for the quality of boiled and fried meat.

1. Pieces of boiled or fried meat should be approximately the same shape and size, soft and juicy.

2. Cutlets should have an oval shape, a flat surface, without cracks, with a golden crust, be soft and juicy.

3. Fried meat and cutlets should have a smell characteristic of fried meat; boiled meat - the smell characteristic of boiled meat and spices.

Practical work

Cooking boiled meat

Inventory and utensils: pan, bowl, cutting board - VM, slotted spoon, spoon, fork, knife.

Product norm: beef - 100, carrots - 2, onions - 2, parsley - 2, salt - 1-2, bay leaf - 1 pc, peppercorns - 1 pc.

Recipe

Put the prepared meat in a saucepan with hot water and bring to a boil. Remove foam, reduce heat and cook over low heat. 30 minutes before readiness, add onions, carrots, parsley, and 10-15 minutes before the end of cooking, put salt, pepper and bay leaf.

Progress Report

1. Determine the quality of the cooked dish.

2. How many products were required for cooking boiled meat per team, and what is their cost?

3. Answer the questions: 1) Why is it put into hot water when cooking boiled meat? 2) How is boiled meat cut into portions?

instruction card. Cooking beef stroganoff

Inventory and utensils: a pot, frying pans - 2, a bowl, cutting boards - CM and CO, a chopper, a knife, a strainer, a wooden spatula, a spoon.

The norm of products: beef - 100, butter - 7, onion - 25, wheat flour - 4, sour cream - 20, tomato puree - 10, salt - 4, pepper - 0.05.

Progress Report

1. Determine the quality of the cooked dish.

2. Answer the questions: 1) What types of heat treatment are used in the preparation of beef stroganoff? 2) Why is meat beaten off before frying? 3) What safety rules and sanitary and hygienic requirements must be observed when cutting products?

Cooking cutlets

Inventory and utensils: frying pan, bowls - 2, cutting boards - CM and CO, meat grinder, pestle, knife, chef's spatula.

Food norm: beef - 50, wheat bread - 9, milk or water - 10, onion - 5, salt - 0.9, crackers - 5, butter - 3, butter - 5 or sauce - 50.

Recipe

Prepare cutlet mass. To do this, you need to wash the meat, get rid of the tendons, cut into pieces and pass through a meat grinder. Pre-soak wheat stale bread in milk or water. Squeeze it out and then combine with chopped meat, add salt, mix everything and again pass through a meat grinder. Thoroughly mix the resulting cutlet mass and beat lightly.

Cut cutlets, breaded in breadcrumbs, put in a hot frying pan and fry on both sides until a crispy crust forms. Cutlets can be brought to readiness in the oven. Put the finished cutlets on a plate (two pieces per serving), pour over melted butter or sauce, put a side dish on them.

Progress Report

1. Determine the quality of the cooked dish.

3. Answer the questions: 1) What is the sequence of cooking cutlets? 2) What safety rules and sanitary and hygienic requirements must be observed when preparing cutlet mass?

Questions and tasks for repeating the topic "Meat"

1. What is the importance of meat dishes in human nutrition?

2. How to determine the good quality of meat?

3. What is the primary processing of meat?

4. What semi-finished products are prepared from meat?

5. What dishes are cooked from boiled meat?

6. What side dishes and sauces are served with meat dishes?

7. What dishes are used for various types of heat treatment! meat?

8. What cold dishes can be prepared from meat?

9. What labor safety rules must be observed during the primary processing of meat?

10. Using table 2, make a lunch menu, which would include the first or second meat course.

11. Make a recipe for your favorite meat dish.

12. Fill in the table.

Questions and tasks for the repetition of the section "Working with food"

1. What is the importance of snacks, first, second and sweet dishes for nutrition?

2. Why is it necessary to comply with sanitary and hygienic requirements and labor safety rules when preparing food?

3. What does it mean to set the table?

4. What is the difference in the preparation of sauce for fish and meat dishes?

5. What dishes are vegetables used for cooking?

6. Why should we not eat the green parts of potatoes and carrots?

7. Tell us about the rules for preparing salads.

8. What snacks can be made from fish?

9. What side dishes can be served with fish dishes?

10. Tell us about the sequence of primary meat processing.

11. What is the difference between stewing meat and roasting?

12. Tell us about the rules for making dressing soups.

13. Fill in the table, listing the utensils, tools and appliances that will be required when preparing dinner.

Categories
- Bakery products
- Dessert
- Diary
- diaries
- Snacks
- canning
- cooking
- Recipes
- Recipes
- With the world on a string

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Basic methods of heat treatment of meat. Heat treatment of meat

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Introduction

1. Purpose of heat treatment

2. Changes in physicochemical parameters and biological value of meat and meat products during heat treatment

2.1 Changes in meat proteins during heating

Effect of temperature and method of heating on the rate and temperature of protein denaturation

Changes in charged groups and pH of proteins during the heat treatment of meat

Change in the solubility of muscle and disaggregation of connective tissue proteins

Protein coagulation and its influence on qualitative changes and structure of meat products

2.2 Change in fat when meat is heated

2.3 Modification of extractives

2.4 Vitamin changes

2.5 Change in water holding capacity

3. Color formation

4. Formation of taste and smell

5. Organoleptic indicators

Conclusion

Literature

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