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Briefly about food processing methods. Processing food before cooking

The main thing when cooking is to preserve as much as possible in the original products nutritious and biologically active substances. To do this, you need to master the rational methods of culinary processing of products. After all, all food products require preliminary or so-called cold processing - sorting, cleaning, washing, soaking, separating inedible parts and final thermal - boiling, frying, stewing, baking and other cooking methods.

The first condition for cooking is strict, strict observance of the rules of sanitation and hygiene. The hostess herself should always be neat, clean, tidy. You should wash your hands, dishes, boards, tools more often, keep the kitchen area clean.

Food must be washed thoroughly

Potatoes and root vegetables - best brushed. Leafy greens - lettuce, sorrel - first you need to sort out, remove the spoiled ones, and then rinse in in large numbers water.

It is very important to learn how to rationally use products, as well as food waste.

When cooking, you need to strive to minimize the loss of nutrients and biologically active substances. If vegetables, for example, are dipped in boiling water, then the loss of vitamins and nutrients while decreasing by 3-5 times.

Frozen meat, when thawed in a large piece, loses less juice than chopped meat.

Heat treatment of products

As a result of heat treatment, new flavoring and aromatic substances are formed in the products, their digestibility increases. In addition, food is rendered harmless, microorganisms die and harmful substances found in some foods, such as the toxin in morels or the solanine in potatoes.

Boiling is the most reliable and widespread way of thermal processing of products. The heating temperature of the product in this case reaches 100 °C.

Products are boiled in liquid, steamed or allowed, i.e. boiled in own juice or with the addition of a small amount of liquid. To obtain concentrated broth, saturated with nutrients and flavors, meat, bones, fish should be poured with cold water, brought to a boil over high heat and then boiled over low heat with a quiet boil.

If you need to get juicy meat, then it is recommended to lower it into boiling salted water, quickly bring to a boil and cook also at a gentle boil until tender.

One of the most important requirements of heat treatment is as follows: it should not be longer than necessary, because during long-term cooking, products almost completely lose biologically active substances, the value of food is significantly reduced, and its taste and aroma deteriorate.

Food frying

When frying, the product is heated without adding liquid with fat, which prevents the product from burning, provides uniform heating, improves the taste of the dish and increases its calorie content.

The main method is frying the product in a small (5-10% by weight of the product) amount of fat. This method is most suitable for home kitchen. At the same time, fat is spread on a very hot frying pan and heated so that it begins to smoke slightly. Slices of meat are lowered into hot fat and fried on both sides. Do not forget that each slice of meat must be dipped in well-heated fat, then the meat will turn out to be fried, juicy and tasty.

If the meat is fried under the lid, it will not brown.

You can deep-fry the product, i.e. in a large amount of fat, when the product to be fried is completely immersed in fat. In this way, brushwood, pies are prepared, potato chips. Deep fried meat is also very tasty.

And here's a tip: put the slices browned on both sides on paper so that the excess fat is absorbed into it.

Grilling products. Grilling

Grilling literally means roasting. This is one of the methods of heat treatment of meat or fish on a skewer - a skewer or a grill - without the use of fat. This method of processing is most acceptable for young meat, especially lamb and pork.

Meat can be roasted over hot coals, in a hot oven, or in an electric grill. By means of infrared rays that emit hot coals or a hot spiral, meat or fish warms up 2-2.5 times faster than when frying in a pan.

On the surface of the product, be it meat or fish, a thin crust is formed during grilling, vessels, pores seem to be sintered, melted under the action of heat, so that the juice does not flow out. That is why the product prepared in this way is juicy, tasty and low-fat.

By the way, doctors consider this method to be the most promising, since, among other advantages, the finished product is less high-calorie.

For roasting in the oven, usually choose big chunks meat (about 1-3.5 kg). The bird is fried whole. Lean meat, before placing it in the oven, is smeared with preheated butter, sour cream or vegetable oil, and fatty ones are sprinkled with water.

Lean meat is first fried in a pan until it forms golden brown and only after that they are placed in an oven at a temperature of 130-150 ° C.

Fatty meat (goose, duck, pork) is placed in an oven heated to 230-240 ° C and kept until browned, after which it is recommended to lower the temperature.

The duration of frying depends on the thickness of the piece and its size. The readiness of the product is determined with a needle or a knitting needle: if the meat is not fried, pinkish juice will stand out from it.

Meat, fish, poultry can be baked in foil. It is best to bake meat and poultry in this way, cut into portions that could be completely wrapped in foil.

Sprinkle meat or fish with salt, add spices and seasonings to taste, and then wrap so that the juice does not flow out, and bake at a temperature of 170-180 ° C for about 20-30 minutes until cooked.

If you bake boiled, fried or otherwise prepared meat, fish or mushrooms, then you will get a dish with a very special taste.

So, in a refractory form or in a pan, you need to put pieces of the product, flavor it with spices and seasonings, pour sauce or wrap with a layer of dough (yeast or puff) and bake in hot oven until golden brown.

Extinguishing food

Foods that do not soften enough when fried, for example, game, old poultry, kidneys, hearts, are usually stewed.

Stewing is a combined method of heat treatment: first, the product is fried, and then boiled in a goose-cooker or any other deep dish, adding seasonings and sauce.

In the pan in which you fried the meat, you need to pour a little water or broth, boil for 2-3 minutes. Pour the product with the resulting juice, adding browned roots, tomato paste, spices and simmer under a lid over low heat or in the oven until tender.

You can stew the product on the stove or in the oven, using fatty broth instead of water - breze. This method is called breezing.

Processing food before cooking

Vegetables, fruits, berries, herbs. Raw products can be contaminated with various pathogenic microflora: larvae of worms, fungi, bacteria. Greens and vegetables grow in direct contact with the ground, all products pass through the hands of many people, but most importantly, they can be eaten raw without cooking. Therefore, all pathogenic microflora, as well as residues of fertilizers and pesticides (if used), must be properly washed off from them.

Greens should be soaked in salted water, changed several times and washed in running water. Fruits and berries, soft vegetables(broccoli, cauliflower and so on.) wash well. This is especially true for strawberries. It is necessary to wash these products by immersing them in water, and then carefully remove them and transfer them to another dish so that sand and dirt remain at the bottom. hard vegetables (beets, carrots, potatoes, turnips, etc.) remove the stalks, wash with a brush, peel. Young vegetables can be consumed with the skin on.

Grains and beans sort out foreign objects, impurities and stones, be sure to rinse thoroughly, sometimes several times. Especially dirty, small ground cereals (millet, wheat, barn, corn).

Meat and fish defrost if necessary and rinse well. Can be cleaned with a knife and cut off places of strong pollution.

Dried fruits need to pour warm water and let stand to free from sulfuric gases with which they are processed for safety, then, if necessary, wash each one separately from sand and dirt.

nuts rinse before use. If you have weak immunity, you can scald with boiling water and dry in the oven.

Wash thoroughly eggs so that what is in the esophagus of the chicken does not get into the food. Store them in the refrigerator in a closed container.

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Culinary processing or simply cooking techniques is a certain action on food in order to give them special properties, which makes them possible for further processing or eating.

From what cooking method we will take as a basis depend:

  • volume of waste; so, when frying meat in pieces, more waste is obtained than when cooking minced meat;
  • the degree of nutrient loss (steaming retains more vitamins than boiling and frying);
  • weight loss (for example, when boiling potatoes, its mass decreases by only 8%, and when deep-fried, by as much as 50%;
  • the taste of dishes (some people like boiled meat, others like fried meat);
  • digestibility of finished products (boiled and poached foods and dishes from them are easier to digest than fried foods).
We choose the cooking method depending on the properties of the product. So, meat taken from one part of the carcass of an animal is suitable for frying, on the other - for cooking. Some vegetables are tastier and healthier in fresh, others - it is better to boil. Using various cooking practices, the hostess can cook completely different dishes from the same source products. There are many more ways to cook food than it might seem at first glance. And it's not just boiling, frying and baking. Everything is much more interesting and complicated. Let's go in order.

Food processing methods:

Classification by cooking stages:

  1. preliminary;
  2. basic;
  3. final.

By way of influence:

  1. Physical:
    1.1 mechanical;
    1.2 thermal.
  2. Chemical.

More about cooking methods:

Preliminary processing

Pre-treatment of products is very milestone which is often underestimated. This stage is especially important in Japanese cuisine and Chinese cuisine. A common way for almost all products is to wash them. Also, almost all products can be crushed. If we take certain types products, the pre-treatment, in particular, includes:

  • for meat: removal of bones, tendons, fat, beating, carbing, breading, marinating.
  • for fish: gutting, cleaning, removal of fins and bones, heads.
  • for poultry: removal of feathers on a bird, gutting, removal of skin, joints.
  • for vegetables and fruits: cleaning, removal of seeds, stalks, eyes.
  • for cereals: washing, sorting, soaking.
  • for flour: sifting.

Basic processing

The main processing ends with the appearance of a new dish in the form in which it was conceived. The dish is ready to eat and fully corresponds to its name. If you were going to cook dumplings with cabbage, then the main processing stage does not end with the preparation of the filling - fried cabbage even though it is already edible. The end will be cooking sticky dumplings. At this stage, different preparation methods can be used.

Final processing

Post-processing can serve different purposes. These include improving palatability ready meal, for which various spices, sauces or flaming are added to the dish; improvement appearance food, which is facilitated by decoration, glazing, tinting, sprinkling with powdered sugar, applying cream (for cakes), decorating with curly pieces of food. Sometimes it is necessary to remove unnecessary components - bones, auxiliary materials (threads, clips, panadas) and eliminate the noticed shortcomings of the dish. This should also include the division into portions. For the same dumplings, the final operations are serving in beautiful dish, greenery decoration.

Chemical processing

At the core chemical processing products may be based on certain biochemical processes (fermentation, fermentation), or cooking is due to the action of certain chemical agents (salting - table salt, pickling - acetic and other organic acids).

physical processing

During the physical processing of products, there is a change in its physical characteristics or the environment in which cooking in progress. The method in which the impact on the product is carried out by changing the physical characteristics of the product itself or the environment. physical processing conditionally subdivided into machining- in which the product is subjected to direct mechanical stress and heat treatment- in which the product is exposed to heat or cold. Heat treatment includes: baking, cooking, steam cooking, extinguishing, frying, roast, baking, open fire treatment, cooking at natural temperature, smoking, cold treatment.

Of course, in each of the groups, their own subgroups can be distinguished, which will include food processing techniques that are close in terms of the expected result. So beating and carbing, related to mechanical processing methods, are used to soften meat at the stage pre-treatment. It should also be noted that some types of food processing can be both basic and preliminary, it all depends on what happens at the end of the operation. For example, pickling can be a preliminary operation (barbecue pickling), and a main operation (mushroom pickling), which results in a ready-to-eat product. You can also make a division into main and auxiliary operations.

Methods of culinary processing of food products

A variety of raw materials and products used in culinary practice, an extensive range culinary products cause a variety of processing methods.

The methods of culinary processing of raw materials and semi-finished products depend on:

The amount of waste; Yes, during machining
potato, the amount of waste is 20–40%, and with chemical – 10–12%

The amount of nutrient loss; for example, when
when boiling potatoes with steam, soluble substances are lost 2.5 times less than when boiling in water;

Mass loss; so, when boiling potatoes, the mass decreases by 8%, and when deep-fried, by 50%;

The taste of the dish (boiled and fried meat);

digestibility of finished products; Thus, dishes from boiled and stewed foods are digested, as a rule, faster and easier than from fried foods.

The choice of cooking method largely depends on the properties of the product. So, some parts of the beef carcass reach culinary readiness only when cooked, while others are enough to fry. Using various methods of culinary processing, the technologist can obtain culinary products with their properties and the appropriate quality.

Methods for processing raw materials and products are classified:

According to the stages of the technological process of production of paired products;

But the nature of the active principle.

According to the stages of the technological process, methods are distinguished:

Used in the processing of raw materials in order to obtain semi-finished products;

Used at the stage of thermal culinary processing of semi-finished products in order to obtain finished products;

Used at the stage of sale of finished products.
By the nature of the active principle, the methods of processing raw materials and products are divided into:

Mechanical;

Hydromechanical;

Mass transfer;

Chemical, biochemical, microbiological;

Thermal;

Electrophysical.

The same processing methods can be used at different stages of the process. Definitions of a number of methods are given in GOST R 50647-94 “Public catering. Terms and Definitions".

These include methods based on mechanical action on the product. Mechanical processing methods can cause rather deep chemical changes in products. So, during cleaning and grinding, the cells of the plant tissue of products are damaged, the contact of their contents with atmospheric oxygen is facilitated, and enzymatic processes are accelerated, which lead to the browning of potatoes, mushrooms, apples, and the oxidation of vitamins. Washing removes not only contaminants, but also some of the soluble nutrients.

Sorting. Products are sorted by size or culinary purpose. Potatoes and root crops are usually sorted by size. This allows you to significantly reduce the amount of waste during further mechanical cleaning. On large enterprises sorting machines are used for this purpose.

Of great importance is the division of products according to culinary use: sorting through the tomatoes, separate whole dense specimens for making salads, crumpled ones - for sauces and soups; parts of the carcasses are divided into those suitable for frying, boiling, stewing, etc.

When sorting, products of inadequate quality and mechanical impurities are removed.

Sifting. Sift flour, cereals. In this case, fractional separation is used: first, larger impurities are removed, and then smaller ones. For this, sieves with holes of various sizes are used. There are metal sieves with stamped holes, wire sieves made of round metal wire, as well as hair, silk, and nylon sieves. In addition to manual sieves, the enterprises use mechanically driven sifters for flour.

Mixing. In the manufacture of many dishes and culinary products, it is necessary to combine various products and obtain a homogeneous mixture from them. For this purpose, mixing is used. So, by mixing minced meat, stale bread soaked in milk or water, pepper, salt, minced meat is obtained.

For mixing, special machines are used - meat mixers, dough mixers, etc. Small amounts of products are mixed manually with special spatulas, oars and other devices. The quality of finished products largely depends on the thoroughness of mixing.

Cleaning. The purpose of cleaning is to remove inedible or damaged parts of the product (vegetable peel, fish scales, crustacean shells, etc.). It is produced manually or with the help of special machines (potato peelers, peeling machines, etc.). For manual cleaning, knives, scrapers, graters and other devices are used.

Grinding. The process of mechanical division of the processed product into parts for the purpose of its better technological use is called grinding. Depending on the type of raw material and its structural and mechanical properties, two grinding methods are mainly used: crushing and cutting.

Crushing is subjected to products with low moisture content (coffee beans, some spices, crackers), cutting - products with high moisture content (vegetables, fruits, meat, fish, etc.) Crushing with a chain of coarse, medium and fine grinding is carried out on grinding machines, special cavitation and colloid mills (fine and colloid grinding).

For grinding solid foods with high mechanical strength (for example, bones), saws are used.

In the process of cutting, the product is divided into parts of a certain or arbitrary shape (pieces, layers, cubes, sticks, etc.), and also finely ground types of products (minced meat) are prepared.

Chopping vegetables (cutting) into parts of certain sizes and shapes is carried out using vegetable cutters, the working bodies of which are knives. various types cutting the product in two mutually perpendicular directions. For grinding meat, fish, meat grinders and cutters are used. The term "chopping" means cutting vegetables into small, narrow pieces or thin, narrow stripes- straw.

Grind raw materials and turn it into a mass uniform in structure

using either special grater machines or manually with graters. This method is used in the production of juices, starch.

To grind products brought to readiness, in order to obtain a puree-like consistency (for rubbing), rubbing machines are used, which have a combined effect on the product: they crush it with blades and at the same time push it through the sieve holes. For manual wiping, sieves with cells of different diameters are used, depending on the type of product.

Pressing. Pressing products is used mainly to separate them into two fractions: liquid (juices) and dense (pulp, pulp). In the process of pressing, the cellular structure of the product is destroyed, as a result of which juice is released. The yield of juice depends on the degree of compression of the product during the pressing process. For squeezing juice, various juicers with a mechanical drive and manual are used.

Pressing is also used to give a certain shape to plastic materials (dough, creams, etc.).

Shaping. This method of mechanical processing is used to give the product a certain shape. Poultry carcasses are molded for greater compactness, cutlets and meatballs, pies and pies, blanks for cookies, etc. This process is carried out manually or using machines: cutlet molding machines, automatic machines for making pancakes, dumplings, dumplings, etc.

Dosing. To obtain culinary products of appropriate quality, it is necessary to strictly follow the established recipes. For this purpose, products are dosed by weight or volume. Dishes, drinks, confectionery are released to visitors of enterprises Catering in a certain amount - in portions (portioning), the mass or volume of which is called "yield". Dosing is carried out manually using measuring equipment, scales, as well as special machines and devices (dough dividers, dispensers and

Breading. This is a mechanical culinary treatment, which consists in applying breading to the surface of a semi-finished product (flour, crumbs, chopped wheat bread and etc.). As a result of breading, juice leakage and water evaporation during frying are reduced, and the finished culinary product has a beautiful golden crust.

Stuffing. This mechanical culinary processing consists in filling specially prepared products with minced meat.

Forcing. Mechanical culinary processing, during which vegetables or other products specified in the recipe are introduced into special cuts in pieces of meat, poultry, game or fish carcasses.

Loosening. Mechanical culinary processing of products, which consists in the partial destruction of the structure of the connective tissue of animal products to speed up the heat treatment process.


1. Technological principles production Catering

1.1 Technological scheme of production and range of catering products

The technological process of production of culinary products consists of a number of stages, or stages, of processing products, which are different in tasks and can be separated in time and space.

The main stages of the technological process are the receipt and storage of raw materials, the production of semi-finished products, the production of finished products and their sale. In public catering, there are enterprises where the technological process is carried out completely, as well as enterprises where the process is limited to several stages. For example, some enterprises accept, store raw materials and produce semi-finished products, while others produce and sell finished culinary products. Often, enterprises use both raw materials and semi-finished products at the same time, and finished products are sold through their own sales departments or other enterprises.

The relatively small scale of production by individual enterprises limits or excludes the possibility of extensive mechanization and automation of the technological process, does not allow full loading and efficient use of the equipment installed on them, and the mechanization of many labor-intensive processes.

Plans for the industrialization of the industry provide for the concentration of production of chilled semi-finished products of a high degree of readiness and chilled ready-made meals at some enterprises and their simple preparation and sale at other enterprises. The concentration of production and the specialization of procurement enterprises make it possible to manufacture products by industrial methods, create the most favorable conditions for the full and purposeful use of waste, and reduce production costs.

Mandatory conditions for the industrialization of the production of culinary products are: production flow in all areas; production of semi-finished products of only a high degree of readiness and finished products; their rapid cooling to a temperature of 10 ° C, as well as the use of unified containers in all areas of production, storage and transportation of products (it is desirable to use it for heating products in pre-cooking rooms).

Favorable conditions for mechanization and automation of production are created at highly specialized enterprises quick service with a significant volume of homogeneous products (patties, dumplings, cutlets, etc.).

Large public catering enterprises have a workshop structure. Shops are specialized according to the types of processed raw materials and manufactured products; their number and functions also depend on the specialization and capacity of enterprises. Warehouse, container, sanitary facilities and some other services are classified as auxiliary industries.

In accordance with the step-by-step description of the technological process, the above concepts - raw materials, semi-finished products, finished culinary products - can be defined as follows.

Raw materials - products, the manufacture of finished culinary products from which is carried out in full technological scheme.

Semi-finished products - products, the manufacture of finished culinary products from which is carried out according to an abbreviated technological scheme. Depending on the completeness of processing, semi-finished products may have a different degree of readiness.

Finished culinary products consist of various culinary and confectionery operated by catering establishments.

A culinary product or dish is a dish with a certain composition of products that have undergone culinary processing.

At different stages of production and consumption of culinary products, waste and technological losses of products are generated.

Technological losses of products - losses of the main part of products during the production and consumption of culinary products: crumbs when cutting bread, wall layer of minced meat and fish on the working bodies of machines, liquid food on kitchen utensils, tableware, etc.

Waste - the remains of products that differ from the main edible part in terms of nutritional or technological advantages: contaminated and rotten leaves of white cabbage, skins of root crops, potatoes, fish scales, impurities in cereals and legumes.

Depending on the subsequent use, waste is divided into food, technical and feed.

Food waste - the remains of products that, after appropriate processing, are used for food (caviar and milt of fish, tops of early beets, and others).

Technical waste - products that are transferred for subsequent use in other industries.

Feed waste - the remains of cooked food, peeling vegetables (potato after starch extraction), inedible parts of fish carcasses and other remains of products that are used for livestock feed. However, not all food leftovers used for livestock feed can be rightfully classified as feed waste.

Wastes are only inedible parts of the finished product: cartilage, tendons, bones, dried fruit seed boxes, etc.

The edible part of the finished product, which the consumer did not use due to the low quality of dishes and products (burnt crust in the roast, oversalted, undercooked or cooled products, etc.), as well as as a result of individual taste and habits (for example, intolerance to meat with increased fat content, the habit of leaving half-eaten food on the plate), should be attributed to direct losses, which should not be in the enterprise.

With the proper organization of the technological process in catering establishments, the amount of waste is reduced.

Currently, many public catering enterprises operate on raw materials or with partial use of semi-finished products.

On fig. 1 shows a diagram of the technological flows of raw materials, finished products, utensils and food waste at a public catering enterprise operating on raw materials:

the raw material coming from the loading platform is sent to the block storage facilities, which is designed for short-term storage of products necessary to ensure the smooth operation of the enterprise. The block consists of cooled chambers for perishable products(meat, fish, herbs, etc.), uncooled warehouses for storing so-called dry products (flour, cereals, sugar, etc.), as well as pantries for storing linen, containers, inventory, etc.;

the processing of raw materials and the manufacture of most semi-finished products are carried out in the procurement workshops - fish, poultry, meat and vegetables, from where the semi-finished products are sent to pre-cooking workshops;

preparation of dishes and culinary products, as well as the preparation of semi-finished products of a high degree of readiness are carried out in cold, hot, culinary and confectionery shops. Ready meals are sent to the dispensing;

sale of finished products and semi-finished products is carried out through shopping room, culinary shops and sponsored pre-cooking enterprises;

from the dining room, tableware enters the washing department, from where it is sent to the distribution room;

waste from all workshops and the washing department is sent to the waste chamber.

The products of public catering enterprises are produced in accordance with the collections of recipes established by the republican and union ministries of trade, which indicate the set and consumption rates of raw materials, the yield of semi-finished and finished products, and the technology for producing the dish. There are collections of recipes for dishes and culinary products intended for dietary nutrition for public catering establishments on manufacturing enterprises and in educational institutions and others.

Public catering enterprises have been granted the right to additionally develop recipes for culinary products, which take into account the specifics of the enterprise, the availability of local raw materials, as well as the taste characteristics of consumers in the region, etc.

The developed recipes are considered at culinary councils and approved by higher organizations that have been granted this right. The recipe approved in this way is used at enterprises subordinate to the organization that approved it (district, region, republic).

The normative information given in the collections of recipes for dishes and culinary products and recipes for culinary products developed by enterprises must comply with the normative material of industry standards, specifications and technological instructions for these products.

Industry standards and specifications determine the quality requirements for raw materials, semi-finished products and culinary products, the conditions and terms of their storage, the rules for packaging and transportation, the procedure for receiving and conditions for sale. IN technological instructions methods of processing raw materials for the preparation of various semi-finished products from meat, fish, poultry and other products are given, as well as recommendations for their proper use.

For the convenience of cooks at enterprises, technological maps are drawn up, in which the amount of raw materials for cooking or culinary products is given per a certain number of servings, taking into account the nature of the enterprise, the availability of inventory, equipment. Technological maps indicate the specifics of the technology of this dish, the yield of the finished dish, garnish and sauce for it, and other information that contributes to the manufacture of products High Quality. The normative material of technological maps corresponds to the approved recipes.

The basis for expanding the range of culinary products in excess of the recipes available in the Collection is the need to increase their nutritional value (biological value, vitamin activity, taste), increase the production of baby and diet food products, the emergence of new products in circulation (new types ocean fish and etc.). At the same time, the interests of the industrialization of the industry require the unification of recipes, limiting the range of culinary catering products to a scientifically justified number of types of products of a certain type, subject to consumer demand and mass production.

1.2 Characteristics of the methods culinary processing of raw materials and semi-finished products

The variety and fluctuations in the composition of products used in culinary practice, an extensive range of culinary products, insufficient unification of recipes and the diversity of equipment determine the multitude of processing methods and wide ranges of its modes. As a result, some methods of processing raw materials and products do not have a strict definition and are descriptive.

The OST on the terminology used in the industry, published by the Research Institute of Public Catering of the USSR Ministry of Trade, only partially eliminated these difficulties.

Methods for processing raw materials and products are divided according to the stages of the technological process or according to the nature of the active principle.

According to the stages of the technological process, there are: methods used at the stage of processing raw materials (they also determine primary, or mechanical culinary processing) in order to obtain semi-finished products; methods used at the stage of thermal culinary processing of semi-finished products in order to obtain finished products; methods used at the stage of sale of finished products.

Raw material processing methods

Methods for processing raw materials include: 1) thawing of frozen products; 2) freeing them from pollution and inedible parts; 3) division of products into parts that require different heat treatment; 4) giving products the required size, shape, condition, arranging them in accordance with the requirements for semi-finished products; 5) impact on products, reducing the duration of their subsequent heat treatment.

Methods (methods) of processing products depend on the nature of the raw materials.

Meat, fish and some other products, mainly of animal origin, are subjected to defrosting.

To remove contaminants, inedible parts and product impurities plant origin sorted (vegetables, cereals), sifted (flour, sugar), peeled (vegetables, less often fruits), cleaned, i.e. cut out spoiled or inedible parts (vegetables, fruits). Animal products are singeed (poultry), gutted, removing inedible components (fish, poultry) and subjected to other processing methods, for example, large blood vessels are cut out of the liver. Products are washed several times.

Products of animal origin are divided into parts that require different heat treatment. The methods of such processing include: dividing the carcass into cuts with the subsequent targeted use of meat, separating muscle tissue from bones (boning), cutting fish into fillets with skin without bones and into fillets without skin and bones, etc.

In order to give semi-finished products the necessary dimensions, shape, consistency and other features inherent in them, the products are cut into pieces, ground in a meat grinder, mixed (for example, to obtain cutlet mass), molded (meatballs, cutlets, etc.), stuffed (patties, etc.) , breading (covering with flour or breadcrumbs), etc.

To reduce the duration of heat treatment, some products (legumes, individual cereals, dried mushrooms) are soaked, the meat is marinated.

Ways of thermal processing of products

During heat treatment, complex structural-mechanical and physico-chemical changes occur in the products, which determine their culinary readiness. In practice, the culinary readiness of products is judged by organoleptic indicators (consistency, taste, smell, color) and the corresponding temperature.

Thermal culinary processing of products has an important sanitary and hygienic purpose. Food products of both animal and vegetable origin are almost always contaminated with microorganisms. During heat treatment, the temperature inside them is usually 80 ° C and above. Although such a temperature does not ensure complete sterility of the product, it has a detrimental effect on most mold and non-spore bacteria, and also causes the transition of spore-forming bacteria into an inactive form.

An important hygienic requirement for all types of heat treatment is the maximum preservation of the nutritional value of products, which is ensured by compliance with the necessary heat treatment regime. Exceeding the established temperatures or duration of heat treatment of products adversely affects their nutritional value.

Heat treatment of products is carried out either in one way (for example, only boiled), or in several ways in various combinations. During heat treatment, the products are given certain technological properties, as well as organoleptic qualities (for example, potatoes are fried before stewing). The most widely used food processing methods in practice are discussed below.

Cooking is a method of heat treatment of products in an aquatic environment (water, milk, broth, broth) or an atmosphere of water vapor.

When cooking in a liquid, the product is completely immersed in it. The temperature of the liquid and the product in conventional cooking pots does not rise above 100-102 °C. To reduce the duration of heat treatment of products, they can be cooked at excess pressure (in autoclaves), however, the temperature should not exceed 130 ° C, otherwise the food qualities of the products, including organoleptic indicators, deteriorate.

Cooking products in an atmosphere of water vapor is carried out in steam ovens at atmospheric or excess pressure. The steam condenses on the product, releases the latent heat of vaporization, heats the product, as a result of which the latter reaches culinary readiness.

Cooking food in a small amount of water, milk, broth, broth or in its own juice is called poaching. The priming is done in a sealed container.

All varieties of cooking are sometimes referred to as wet heat.

With all methods of cooking products, a part of the substances contained in them passes into the environment. nutrients- extractive, mineral, carbohydrates, vitamins, nitrogenous compounds. The largest amount of soluble substances passes from the products into the liquid when they are completely immersed, the smallest - when poached and steamed.

When cooking with steam, soluble substances are lost irretrievably, since condensate is not used. It should also be remembered that the longer the product is cooked, the more soluble substances it loses.

One of the promising methods of heat treatment in the conditions of centralized production of ready-made chilled or frozen dishes is microwave heating, i.e. product processing in the microwave field. A feature of this heating is the simultaneous heating of the product throughout the entire volume, as a result of which the time for bringing most products to readiness is sharply reduced and amounts to several minutes. During this time, the temperature inside the product can rise to 100 °C, but since the temperature of the outer layers, which emit part of the heat to the environment, does not exceed 100 °C, no brown crust forms on the surface of the product.

The heating of finished products in microwave ovens at the places of consumption can be carried out in compliance with the highest sanitary and hygienic requirements and quickly.

Frying is a method of processing products in direct contact with fat or without fat at a temperature that ensures the formation of a specific crust on their surface.

The method of short-term frying of products without bringing them to culinary readiness in order to give the finished products certain properties is defined by the term frying.

The taste and aroma of fried foods are determined by substances contained mainly in a specific golden crust on the surface. fried foods. Its formation is due to the fact that in the process of frying the outer layer of the product under the action of high temperature dehydrated and heated to temperatures above 100 °C. At the same time, the substances contained in the dehydrated layer undergo complex physical and chemical changes, * as a result of which new chemical compounds are formed that have the color, taste and aroma of fried.

If you continue to fry the product after the formation of a ruddy crispy crust, then substances with an unpleasant odor and taste of burnt appear, which can adversely affect gastrointestinal tract especially children.

Under normal frying conditions, only a very thin outer layer of the product is under dry heating conditions and forms a fried crust, the temperature of the bulk of the product does not exceed 100 ° C, and it is stewed in its own juice.

The methods of frying foods used in culinary practice differ depending on the type of heat transfer: in some cases, radiation plays a decisive role (radiant heat transfer), in others, heat conduction (a heat transfer agent, for example, fat). It should be borne in mind that fat is absorbed to some extent by the fried product and affects its quality.

Frying food with a small amount fat is produced in an open shallow dish. The mass of fat is 5-10% of the mass of the product. The fat is heated to 150-180 ° C, after which the product is placed in the dishes. A thin layer of fat between the product and the bottom of the dish promotes uniform heating of the product and prevents it from burning. After the formation of a crispy crust on the side in contact with fat, the products are turned over to the other side.

The temperature regime and duration of frying vary depending on the type of product.

Raw foods are fried fully prepared or semi-prepared, followed by heat treatment in an oven.

TTDDri deep-frying (fat for frying) products are completely immersed in fat, the amount of which is 4-5 times or more greater than the mass of the product. Such an amount of fat allows not only to completely immerse the frying product in it, but also to prevent the fat from cooling at the beginning of the process, which can worsen the frying conditions. In continuous fryers, the ratio of fat:product is 20:1. For deep frying, deep fryers or other devices specially designed for this purpose are used.

Fat is heated to a temperature of 175-190 ° C, which ensures good conditions heat transfer, rapid and uniform formation of a crispy crust over the entire surface of the product. The temperature regime and duration of frying are different depending on the type of product.

Deep-fried potatoes, fish, pies, donuts and other products are fried. J7

For frying in the oven, the products are placed on baking sheets, pans or in special metal molds with a small amount of fat and placed in an oven, the temperature of which is regulated. The heating of the product occurs due to radiation from the emitters and heated surfaces of the chamber and partly due to the thermal conductivity of the hot hearth and convection of moving air flows.

Tests of devices with forced convection of heated air showed the possibility of using them for heating quick-frozen and ready-to-cooled dishes and for preparing a wide range of meat, fish, vegetables and dough products with high productivity and economy.

Bringing flour or confectionery products to full readiness in special baking ovens or ovens is called baking.

When frying food in electric grills, IR emitters are used. Infrared rays are able to penetrate into the thickness of the fried product to a certain depth, which ensures rapid heating not only of its surface, but also of deep layers, as a result of which the time of thermal processing of products is significantly reduced.

Stewing - products intended for stewing are pre-fried until half cooked, and then stewed with the addition of spices, seasonings or sauce. For stewing, use a sealed container.

Roasting is a method of heat treatment of products in an oven until culinary readiness and the formation of a golden crust on the surface of the product.

Bake, as a rule, products that have undergone preliminary heat treatment. They are placed in pans or on baking sheets and kept in an oven at a temperature of 200-250 ° C until a golden crust forms on the surface. Some types of food (fish) are baked raw.

Frying boiled foods produced with a small amount of fat or deep-fried.

Sauteing - frying some products with or without fat at a temperature not exceeding 120 ° C. Saute, for example, aromatic roots, onions, carrots, flour with fat (it is also sauteed without fat).

Blanching (scalding) is a short-term (1-5 min) exposure to products of boiling water or steam. The products are blanched to facilitate their subsequent mechanical processing (scalding of sturgeon fish), the destruction of enzymes that have an undesirable effect on products peeled from surface shells (some fruits), and the removal of bitterness (cabbage).

Portioning of culinary products

Portioning of culinary products is carried out manually using various dispensing equipment, for example, production spoons for portioning first courses, garnish, sauces, salad forms, vinaigrettes, etc. At the portioning stage, dishes and products are given, also manually, a marketable appearance.

In the conditions of in-line production, the issue of automation of portioning or dosing of culinary products is extremely relevant. The most accessible is the volumetric automatic dosing of "single-phase" liquid drinks (coffee, jelly, etc.) and more viscous products (sauces, sour cream, puree soups). Automation of portioning of viscous and crumbly cereals, dressing soups, salads, fried potatoes and other dishes and products with "multi-phase" and other complex structures are currently under development.

The solution to this problem is difficult due to the complexity and high cost of automation systems, insufficient manufacturability of a number of culinary products, the need to clarify and change the size of tolerances for the mass of dishes and products and the methodology for their control.

Subdivision of food processing methods according to the nature of the active principle

By the nature of the active principle, the methods of processing products are divided into mechanical, hydromechanical, thermal, electrophysical, chemical and biochemical.

Mechanical methods of processing products include sorting, sieving, sizing, crushing, cutting, rubbing, dosing, shaping, whipping, etc.

Hydromechanical methods of processing products - washing, soaking, filtering.

Thermal methods of processing products are associated with heating, cooling.

Electrophysical methods of processing products are microwave heating, IR heating.

Chemical and biochemical methods of food processing include potato sulfitation, meat pickling, adding soda, ammonium carbonate to the dough, enzymatic meat processing.

1.3 Technological support of the quality of culinary products quality of culinary products

The quality of culinary products is understood as the totality consumer properties that determine its suitability to satisfy people's need for rational nutrition. The most significant single indicators of the quality of culinary products include harmlessness, high nutritional, taste and commercial qualities.

The safety of culinary products is ensured through strict observance of the sanitary and hygienic requirements for the production of culinary products, including the methods and modes of food processing, at all stages of the technological process.

The high nutritional value of culinary products in the optimal variant determines its compliance with the composition of a balanced nutrition formula. However, almost every type of culinary product has its own nutritional advantages, as a rule, different from the balanced nutrition formula, which complicates the preparation of a physiologically balanced diet based on it.

Many dishes and culinary products that make up the main range of products manufactured by public catering enterprises need to increase their nutritional value by increasing their content of vitamin C, some B vitamins, better balance of the amino acid composition of proteins in terms of their total content, as well as the amount of polyunsaturated fatty acids.

The high taste qualities of food are those of its indicators that we perceive organoleptically, to which we are accustomed and with which our ideas about tasty, well-cooked food are associated.

According to the usual organoleptic perceptions, the culinary readiness of food is determined.

Food should always be tasty, and the professional level of a modern catering engineer is determined not by the ability to invent dishes, but by the ability to correctly conduct the technological process of food processing and prepare delicious meals. “That is useful and nutritious, that is pleasant and tasty,” said I.P. Pavlov.

In order to satisfy the individual tastes of consumers, catering establishments also need a variety of products in the range.

The desirability and convenience of consumption of culinary products determine its high commercial value. In order for the products to meet this quality indicator, for example, cabbage for minced meat is chopped, and not chopped into strips, but smoked sausage cut into thin slices.

It is important that these product quality indicators have a quantitative expression and an established average level that must be maintained throughout the entire time of product sales. The established level not only determines the quality of products, but is also the starting point for improving the technology of its production.

Examples of this level are marginal norms the content of fat oxidation products in deep fat (no more than 1%), as well as data on the composition of culinary products presented in the third volume of the reference book "Chemical composition of food products" (M .: Light and food industry, 1984).

In addition, nutritional, taste and commercial qualities in the overall assessment of product quality should be of equal importance, i.e. we cannot say that food should be healthy and not necessarily tasty, or vice versa. With the improvement of technology, it is possible to improve one or more indicators of the quality of a particular product, but at the same time, the remaining indicators must correspond to the established level.

A necessary condition for assessing the quality of culinary products or improving its technology is also the reproducibility of the latter, i.e. the wording of the recommended methods and processing modes should be such that different specialists can prepare equivalent products using this technology, regardless of its quantity.

Product quality indicators are set various methods: experimental, calculated, organoleptic, sociological, expert, in the order accepted for them.

The assessment of the quality level can be carried out by a differential method based on single quality indicators, a complex method using a generalizing quality indicator (for example, energy intensity of products) or a mixed method. It should be remembered that only with strict observance of these provisions can one objectively assess the merits of a particular technology and the quality of products manufactured on its basis.

recommendations for beating and other methods of machining semi-finished meat products in order to reduce the duration of heat treatment and improve the organoleptic characteristics of finished products, etc.

An example of the unreasonable extension of the features of the technology of dietary products to the technology of dishes normal diet are recommendations to avoid browning of roots and onions in the production of dressing soups in order to avoid heating and undesirable changes in fat. However, to exclude this process from the technology of dishes for healthy people it is impractical, since if the regimes established for sauteing the roots and onions are observed, the fats practically do not change, and the taste of the finished product improves significantly.

In the process of improving the technology of certain dishes, changes in their recipes are possible.

In the case of small quantitative changes that do not noticeably affect the taste and commercial qualities inherent in this dish, the name of the dish is retained, and the refined or newly recommended methods and modes of processing products are an improved technology for the original dish. This is also confirmed by the practice of public catering enterprises. So, according to the Collection of Recipes for Dishes and Culinary Products for Public Catering Establishments, the norms for laying the main vegetables (potatoes, cabbage, beets, etc.) given in hot soup recipes can be increased or decreased by no more than 10-15%, provided that total weight planted vegetables. The name of the dish does not change.

If significant qualitative changes are made to the product recipe, then we should not talk about improving the technology of the original dish, but about creating a new dish with its own production technology and quality indicators. Preservation of the old name for a new dish is unacceptable.

An example of improving the technology of dishes and products with minor changes in the recipe that are not of a fundamental nature are the recommendations for adding 7-10% soy flour to the recipe of deep-fried dough products (donuts, pies). Additives of soy flour increase the nutritional value of products, accelerate the process of formation of a fried crust on the surface of products, which makes it possible to reduce the temperature of deep-frying and shorten the duration of the frying process. At the same time, the chemical stability of the fat is increased.

A qualitative change in the recipe takes place, for example, when adding Shkolnaya 10% to the dough for a bun carrot puree in order to improve the baking properties of dough and commercial qualities finished product. Therefore, the bun, made according to the new recipe, received a different name - Autumn.

It is promising to improve the quality of culinary products and improve the technology of its production by improving the balance of food components in dishes and products, the directed use of the technological properties of products and the observance of technological patterns of production.

The development of recipes with improved balance of nutritional components increases the efficiency of product use. In the works carried out in this direction by I.I. Kovalev and other researchers showed that there are reserves in improving the balance of the protein component of milk and cereals in milk porridge recipes, the best combination garnish and fish fish dishes. M.G. Kerimova has developed more than two dozen recipes for cereal and flour dishes, in which protein utilization is no worse than in egg and dairy dishes.

In vegetables, during the heat treatment, vitamin C is largely destroyed, therefore, recommendations for adding parsley, celery, dill or green onions to many vegetable dishes, expressed in the form of a wish in the Collection of recipes for dishes and culinary products, should become mandatory in practice.

Raise taste merits culinary products is associated with their quantitative assessment. At present, it is possible to supplement the normative data on the content of sugar, salt, acid and other flavoring components in dishes and culinary products with the rheological characteristics of products, which are important for the calculation of machines and apparatus in the conditions of industrialization of the industry.

Technological properties of products

Technological characteristics, or technological properties, of raw materials, semi-finished products and finished products are manifested during their technological processing. They can be divided into mechanical (strength), physical (heat capacity, density, etc.), chemical properties (change in composition, formation of new substances) and structural features (mutual arrangement and interconnection of parts or components that make up the product).

Separate categories of technological properties are described by instrumental or organoleptic methods. For example, the mechanical properties and features of the structure of products can be quantitatively described by structural and mechanical indicators adopted in rheology (tensile strength, elasticity, elasticity). At organoleptic evaluation these properties, terms such as “tender” meat, “airy” pudding, “thick” sauce, etc. are used. The physical and chemical properties of products can be quantitatively described by the density, color, composition of the products; in the organoleptic evaluation of these properties, such terms as "sour", "sweet", "aromatic", and others, are used. physical and chemical properties products.

Technological properties determine the suitability of products for a particular processing method and the change in their mass, volume, shape, consistency, color and other indicators during processing, i.e. formation of the quality of finished products.

The technological properties of heat-treated products differ from those of raw products. Thus, the strength of the tissue of raw root crops allows them to be cleaned mechanically, and the strength of the tissue of boiled root crops (an order of magnitude lower) does not allow this.

In the conditions of industrialization of the industry, the manufacturability of raw materials, semi-finished products and finished products is of great importance, i.e. their suitability or adaptability to modern industrial processing methods with minimal labor costs.

High manufacturability has, for example, potatoes with tubers of the correct form and a shallow occurrence of eyes, which allows them to be subjected to mechanical cleaning with a minimum amount of waste. High suitability for industrial processing methods have minced masses from meat, fish and other products; it is convenient to portion liquid homogeneous products, etc.

Any new raw material must be technologically studied. Based on knowledge of the technological properties of products and their reasonable use, it is possible to improve the quality and technology of culinary products.

The results of the study of the formation mechanism and technological properties of protein-polysaccharide complexes made it possible to develop a science-based technology for vegetable-based sauce pastes with vegetable oil that do not delaminate when heated.

Taking into account the technological properties of polysaccharides and proteins, it is proposed new way clarification of broths with carrots, where the active principle is the pectin substances of the root crop.

Studies of the behavior of vegetable cell wall polysaccharides during heat treatment made it possible to explain the specifics of the effect of medium acidification on the digestibility of various vegetables and fruits, as well as the specifics of beet tissue softening during heating and cooling. This also made it possible to develop and recommend recipes and technology for vegetable gelled products.

Structural and mechanical properties of cutlet mass from meat and vegetables served as the basis for refining the recipe of the mass with a view to its suitability for processing on equipment existing in the industry.

Based on the study of the technological properties of vegetables, recipes and technology for the production of products from dough with a reduced calorie content have been developed.

An example of improving the manufacturability of products and creating on this basis an industrial method for the production of culinary products is a new method for making cabbage rolls, which involves chopping cabbage, mixing it with other components, followed by dosing and forming a mass in a sausage casing.

The technological properties of products are determined by the composition and structure of the food substances that form them, the relationship of these substances in the individual structural components of the products, i.e. we can say that the behavior and change of food substances that form products during heat treatment together determine the technological properties of the latter.

Therefore, in order to avoid duplication of material, it is advisable to separately consider the behavior and changes during the culinary processing of certain nutrients that we encounter in practice during the processing of many products, and consider specific changes in nutrients and the structure of products in general in the sections that describe the culinary processing of these products. .

Protein changes

Changes in proteins that are observed during the production of semi-finished products and thermal culinary processing of products affect the yield, structural-mechanical, organoleptic and other indicators of product quality.

The depth of physicochemical changes in proteins is determined by their natural properties, the nature of external influences, the concentration of proteins, and other factors.

The most significant changes in proteins are associated with their hydration, denaturation and destruction.

Protein hydration

There are so-called polar groups on the surface of native protein molecules. Water molecules also have polarity, and they can be represented as dipoles with charges at the ends that are equal in value but opposite in sign. Upon contact with a protein, water dipoles are adsorbed on the surface of the protein molecule, orienting themselves around the polar groups of the protein. Thus, the main part of the water, more or less firmly bound in food by proteins, is adsorption. There are two types of adsorption: ionic and molecular. This is explained by the constant presence on the surface of the protein molecule of two types of polar groups: free and bound.

Free polar groups (amino groups of diamino acids, carboxyl groups of dicarboxylic acids, etc.) dissociate in solution, determining the value of the total charge of the protein molecule. The adsorption of water by ionized free polar groups of a protein is called ionic adsorption.

Related polar groups (peptide groups of the main polypeptide chains, hydroxyl, sulfhydryl, etc.) attach water molecules due to the so-called molecular adsorption.

The value of molecular adsorption of water is constant for each type of protein, the value of ionic adsorption changes with a change in the reaction of the medium. At the isoelectric point, when the degree of dissociation of protein molecules is minimal and the charge of the protein molecule is close to zero, the ability of the protein to bind water is the lowest. When the pH of the medium shifts in one direction or another from the isoelectric point, the dissociation of the basic or acidic groups of the protein increases, the number of protein molecules increases, and protein hydration increases. In the technological process, these properties of proteins are used to increase their water-binding capacity.

Adsorption water is retained by proteins due to the formation of hydrogen bonds between their molecules and water (between the hydrogen atom of one molecule and the oxygen atom of another). Hydrogen bonds are weak, but this is offset by a prudent number of bonds: each water molecule is able to form four hydrogen bonds, which are distributed between the polar groups of the protein and neighboring water molecules.

As a result, the adsorption water in the protein turns out to be quite strongly bound: it does not separate from the protein spontaneously and cannot serve as a solvent for other substances.

In low concentration solutions, protein molecules are completely hydrated due to the presence of an excess amount of water. Such protein solutions are found in milk, batter, in some mixtures based on egg melange, etc.

In concentrated protein solutions and watered protein jellies, when water is added, additional protein hydration occurs (within known limits).

Additional hydration of proteins in concentrated solutions is observed, for example, when added to the egg mass intended for the manufacture of omelettes, water or milk.

In jelly, protein molecules, with the help of intermolecular bonds of different nature, form a spatial network, in the cells of which the amount of water that is quite specific for a given protein is retained.

The ability of a protein to form jelly is determined by the configuration of its protein molecules. The greater the asymmetry of protein molecules (the ratio of length to thickness or diameter), the lower the protein concentration is necessary for the formation of jelly. Water immobilized in the cells of the spatial grid of the jelly participates in the formation of its structure, approaching the structure of a solid body (the jelly is able to retain its shape, mechanical strength, elasticity, plasticity). From this it is clear why the protein jelly of most products is more watered than concentrated solutions. For example, myofibrils of muscle fibers of warm-blooded animals contain 15-20% of proteins, in sarcoplasm - 25-30%.

Protein hydration is of great practical importance in the production of semi-finished products: when water, table salt and other substances are added to crushed animal or vegetable products and when the crushed components are mixed, protein hydration consists of simultaneously dissolving and swelling processes. With hydration, the stickiness of the mass increases, as a result of which it is well molded into products (semi-finished products) intended for thermal cooking.

Additional hydration of proteins occurs when water is added to minced meat in a meat grinder. 10% of the mass of meat is added to chopped steaks and meatballs, 20% to minced meat for dumplings.

Dry proteins of flour, cereals, legumes, contained in products in the form of particles of dried cytoplasm and aleurone grains, swell upon contact with water, forming a continuous more or less watered jelly. A classic example of this type of hydration is the preparation of dough, during which flour proteins swell when in contact with water, forming gluten. The rheological properties of the dough, prepared on the basis of flour and water, largely depend on the ratio of these components. The degree of hydration of proteins largely determines such an important indicator of the quality of the finished product as juiciness, and other criteria for organoleptic evaluation associated with it. When evaluating the role of hydration processes, it must be borne in mind that in food products, along with adsorption water, strongly bound by proteins, there is a greater or lesser amount of osmotically and capillary-bound water, which also affects product quality.

Protein denaturation

Denaturation is a violation of the native spatial structure of a protein molecule under the influence of external influences.

Such external influences include heating (thermal denaturation); shaking, whipping and other sharp mechanical effects (surface denaturation); high concentration of hydrogen or hydroxide ions (acid or alkaline denaturation); intensive dehydration during drying and freezing of products, etc.

For the technological processes of production of public catering products, the thermal denaturation of proteins is of the greatest practical importance. When proteins are heated, the thermal motion of atoms and polypeptide chains in protein molecules increases, as a result of which the so-called weak cross-links between polypeptide chains (for example, hydrogen ones) are destroyed, and hydrophobic and other interactions between side chains are also weakened. As a result, the conformation of the polypeptide chains in the protein molecule changes. In globular proteins, protein globules unfold with subsequent folding in a new type; strong (covalent) bonds of a protein molecule (peptide, disulfide) are not violated during such a rearrangement. Thermal denaturation of collagen fibrillar protein can be represented as melting, since as a result of the destruction of a large number of cross-links between polypeptide chains, its fibrillar structure disappears, and collagen fibers turn into a continuous vitreous mass.

In the molecular rearrangement of proteins during denaturation, an active role belongs to water, which is involved in the formation of a new conformational structure of the denatured protein. Completely dehydrated proteins isolated in crystalline form are very stable and do not denature even when heated for a long time to a temperature of 100 °C and above. The denaturing effect of external influences is the stronger, the higher the hydration of proteins and the lower their concentration in solution.

Denaturation is accompanied by changes the most important properties protein: loss of biological activity, species specificity, ability to hydrate (dissolve, swell); improved attack by proteolytic enzymes (including digestive ones); increasing the reactivity of proteins; aggregation of protein molecules.

The loss of biological activity by proteins as a result of their thermal denaturation leads to the inactivation of enzymes contained in plant and animal cells, as well as to the death of microorganisms that enter products during their production, transportation and storage. In general, this process is assessed positively, since the finished product, in the absence of its re-contamination with microorganisms, can be stored for a relatively long time (in chilled or frozen form).

As a result of the loss of species specificity by proteins, the nutritional value of the product does not decrease. In some cases, this property of proteins is used to control the technological process. For example, by changing the color of the meat chromoprotein - myoglobin from red to light brown, the culinary readiness of most meat dishes is judged.

The loss of the ability of proteins to hydrate is explained by the fact that when the conformation of polypeptide chains changes, hydrophobic groups appear on the surface of protein molecules, and hydrophilic ones are blocked as a result of the formation of intramolecular bonds.

Improvement of hydrolysis of denatured protein by proteolytic enzymes, increase of its sensitivity to many chemical reagents is explained by the fact that in the native protein peptide groups and many functional (reactive) groups are shielded by an external hydration shell or are located inside the protein globule and thus protected from external influences.

During denaturation, these groups appear on the surface of the protein molecule.

Aggregation is the interaction of denatured protein molecules, as a result of which intermolecular bonds are formed, both strong, for example, disulfide, and numerous weak ones.

The consequence of the aggregation of protein molecules is the formation of larger particles. The consequences of further aggregation of protein particles are different depending on the protein concentration in the solution. In low-concentration solutions, protein flakes are formed that precipitate or float to the surface of the liquid (often with the formation of foam). Examples of this type of aggregation are the precipitation of flakes of denatured lactoalbumin (when milk is boiled), the formation of flakes and foam of proteins on the surface of meat and fish broths. The concentration of proteins in these solutions does not exceed 1% *

When proteins are denatured in more concentrated protein solutions, as a result of their aggregation, a continuous jelly is formed that retains all the water contained in the system. This type of protein aggregation is observed during heat treatment of meat, fish, eggs and various mixtures based on them. The optimal protein concentration at which protein solutions form a solid jelly under heating conditions is unknown. Taking into account that the ability of proteins to form gels depends on the configuration (asymmetry) of molecules, it must be assumed that the specified concentration limits are different for different proteins.

Proteins in the state of more or less watered jellies are compacted during thermal denaturation, i.e. their dehydration occurs with the separation of liquid into the environment. The jelly subjected to heating, as a rule, has a lower volume, mass, plasticity, as well as increased mechanical strength and greater elasticity compared to the original jelly of native proteins. These changes are also a consequence of the aggregation of denatured protein molecules. The rheological characteristics of such compacted jellies depend on the temperature, pH of the medium and the duration of heating.

The denaturation of proteins in jellies, accompanied by their compaction and separation of water, occurs during the heat treatment of meat, fish, cooking legumes, and baking dough products.

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    general characteristics pickles, their types. Preparation of products, raw materials and semi-finished products. The technology of preparing dishes according to the assortment (recipe, quality requirements). Terms of storage and sale. Cooking as a method of heat treatment.

    term paper, added 01/16/2014

    Food safety issues. Modification, denaturalization of food. Nitrates in food raw materials. Characterization of toxic elements in raw materials and finished products. Requirements for the sanitary condition of raw materials and food production.

    term paper, added 10/17/2014

    Nutritional value of products used for cooking and culinary products Ukrainian cuisine. Assortment and recipes of dishes, features of preparation, design and serving. Methods and processes of technological processing of products, quality control.



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