Chemical processes during cooking. Physics Specialty Food Product Technology

About 80. % food products run by one or another thermal processing, in which it increases, however, to certain limits, digestibility, the products are softened, which makes them available for chewing. Many types of meat, legumes and a number of vegetables would disappear in general from our food if they were not exposed to thermal processing. The impact of heat leads to the destruction of harmful microorganisms and some toxins, which ensures the necessary sanitary and hygienic safety of the products, primarily animal origin (meat, bird, fish, dairy products) and rootfields. Thus, thermal processing increases the microbiological durability of food products and extends their storage. In the heat treatment of some products (for example, gentlebobobic, eggs), inhibitors of the enzymes of the human digestive tract are destroyed, in the processing of grain (especially corn) vitamin PR (niacin) from a non-active inactive form - niacin. Finally, an important factor is that various types of thermal processing make it possible to diversify the taste of products, which reduces their "transcription".

However, all this does not mean that the thermal processing of products is not devastable. With heat treatment, vitamins and some biologically active substances are destroyed, proteins, fats, minerals can be treated and destroyed and destroyed (polymerization products of fats, melanoidins, etc.). Thus, the task of rational cooking is that the necessary goal is achieved with the minimum loss of the beneficial properties of the product.

Given the features of the preparation of plant and animal products, consider them separately.

Vegetable products

A distinctive feature of vegetable products is the high content of carbohydrates in them: over 70% of dry substances. Therefore, consider them in more detail.

The absolute majority of plant products used in human nutrition are parts of plants with alive parenchymal cells, in which they contain substances that are of interest from the point of view of nutrition: mono and oligosaccharides and starch. These cells have a primary shell consisting of low molecular weight cellulose and low molecular weight fractions of hemicellulose, an important distinctive feature of which is the predominance between the structural units of the B-1,4-Communication, and it is this connection that is not destroyed by the digestive enzymes of man. In the median plate and interclauders are pectin substances, which are based on the remnants of D-galacturonic acid, interconnected by B-1,4-bonds (this connection is also not destroyed by human digestive enzymes). However, depending on the phase of the development of a living cell, the degree of polymerization can fluctuate: from 20 to 200 or more residues. With an increase in the degree of polymerization, the solubility of pectin substances in water is reduced and mechanical strength increases. The so-called protopectin, with which the mechanical strength of fruits, berries and vegetables is associated, is in reality high molecular weight of pectin, which forms a secondary structure due to the binding of water, which, due to the special properties of the bound water, gives hardness to plant products. At the same time, all plants contain active pectinstorerase and less active polygalactures. At a certain period of the life of the plant, these enzymes are activated and begin to destroy the secondary structure of pectin to form low molecular weight pectins and water. In this case, the product softened. This enzymatic process may occur during storage. Since the primary wall is extremely permeable, and the secondary and moreover, there are no tertiary walls in living cells, formed under the action of pectolytic enzymes, low molecular weight pectin and water are partially moving into cell protoplasm.

Thermal treatment of vegetable products containing a noticeable amount of pectins (vegetables, fruits, potatoes, roots) is also aimed at destroying the secondary structure of pectin and partial release of water. This process begins at a temperature of above 60 ° C and then accelerated by about 2 times each 10 ° temperature increase. As a result, in the finished product, mechanical strength decreases more than 10 times. For example, mechanical strength in compression of raw potatoes is 13-10 a pa, boiled - 0.5-10 th, beets - respectively 29.9-10 s and 2.9-10 5 pa.

It should be noted that the mechanical strength of plant products also depends on the content of water in them. The smaller in the free water product, the greater its strength under other equal conditions. (Sublimated products do not contain free water and have high mechanical strength, which is reduced during their hydration.) Water release during the destruction of protopectin also contributes to the softening of the product.

Taking into account the above, consider the basic processes occurring during thermal culinary processing. When cooking, in addition to the thermal decay of the secondary structure of pectin, the saturation of cells is saturated with water (the introduction of water in proteins, pectins, starch). At the same time, gelation of the formation to Rachmal and low molecular weight pectin is of particular importance, which, at a temperature of ure, 60--80 ° C inside the product become partially soluble in water. Although the starch remains in the plasma of the cell, and the pectin-- in the intercellular space, the extraction of starch and pectin occurs not only from surface destroyed cells, but also from the inner layers. At the same time, with cooking, a number of water-soluble substances (sugars, amino acids, organic acids, minerals and vitamins) are extracted from the layers of the product in contact with water.

In general, during cooking often there is an absolute loss of water, the value of which depends on the nature of the product (for example, when cooking potatoes 2--6%, the cabbage is 7--9%, which is explained by the destruction of the secondary structure of pectins).

The duration of cooking depends on the temperature and size of the product. When cooking under pressure, when the temperature rises against the usual 2--3 °, the duration of cooking is reduced by about 1.5 times. Small pieces are heated to 70--80 ° C throughout the volume faster than large, but the extraction of water soluble substances increases. Therefore, the degree of grinding should not be strong. In practice, the optimal modes of cooking duration and the degree of grinding of the product are established.

Cooking of crude products (beets, carrots, potatoes in the peel) is not reflected on the duration, but leads to a noticeable decrease in the loss of food substances, since a dense surface layer (epidermis, periderma) prevents extraction.

Cooking for a couple also reduces the loss of food substances compared to cooking in water, since the extraction is only with the surface layers themselves.

With frying occurs, mainly the thermal decay of the secondary structure of pectins to form soluble pectins and water. Starch grains and low molecular weight pectin begin to react with water and partially go to the gel-like state. However, if the evaporation of water from the product during frying occurs quite intensively, the gel dries, and the product becomes solid again, its mechanical strength increases several times.

Often, frying is carried out in a large amount of fat (in deep fryer). In fact, this is not frying, but grated in fat. At the same time, the temperature of the medium turns out to be higher than with conventional cooking, the softening occurs faster. There are few fat soluble substances in plant products, therefore, the loss of food substances with frying is insignificant, except, of course, disintegrating vitamins.

Thermal treatment of plant products containing a significant amount of pectin, but a lot of starch (grain, gentle-born) is accompanied by starch tierzing and is usually in cooking in water. The absorption of water, the braeshery-tested starch reaches 100-200%.

Shpak Oksana and Mizinova Alena

Relationship of chemical processes and technology cookingin molecular cooking

Shpak Oksana, Mizinova Alena

GBOU from NGO "PL № 8" Group 36 "Cook, Confectioner", Saratov

Scientific leaders: Drowner Svetlana Vladimirovna, Master of Industrial Training and Bulatova Tatiana Vitalevna, Chemistry Lecturer

Any science does not stand still, along with them and technology. Today, innovation has covered all the spheres of human life, did not pay attention and cooking. Cooking is the activity you need to know from all sides.

In our work, we put forward hypothesis: the modern development of cooking is impossible without knowledge of chemistry and biology.

We started my research with a survey of students of the II-III courses of the Lyceum by the profession "Cook, Confectioner". 42 people took part in the survey. Based on the data obtained, the following conclusions can be drawn. Most respondents are confident that the modern cook should know the foundations of chemistry, since without it it is impossible to be a highly qualified specialist in its field of activity. Also, ¾ respondents have an idea of \u200b\u200bthe molecular cooking and most of them received these knowledge in the lyceum, participating in extracurricular activities.

When cooking, many of the operations used in chemistry are used: weighing, grinding, mixing, heating, dissolution, filtering.

It is unlikely to engage in molecular cooking everywhere. First, not every guest is capable of accepting such innovations and make themselves even try so unusual dishes, secondly, it is too expensive. Equipment for such a cooking costs thousands and even millions of dollars, not every restaurant is on the pocket.

Having studied the theoretical and practical aspects of this topic, we did the following conclusions: it is safe to say that the hypothesis is fully confirmed, chemistry, biology and cooking are an example of coordinated and friendly work.

Even the best and proven recipe does not guarantee that the result is a great dish. Too many secondary factors affect the final product. In order to never be disappointing in their own culinary talents, it is enough to own the most superficial knowledge in chemistry.

Gradually, these new ideas, technologies and methods penetrate the culinary books, recipes are adapted and taken to armared by the food industry - and, finally, new dishes appear on the grocery store shelves, as it happened with the dishes of "new cooking" or fusion style. And it is possible that after ten years, the technologies used in scientific gastronomy, like a quick frost in liquid nitrogen, will be used in the home kitchen.

Download:

Preview:

Hello! I am a student professional lyceum number 8 of the city of Saratov Shpak Oksana! The topic of my research work

The relationship of chemical

Introduction of processes and technologies of cooking dishes in molecular cooking

I chose this topic because she was interested in me in the course of my participation in the binary lesson and in extracurricular events held on this subject in the lyceum.

An object Studies of this work of molecular cooking dishes.

Subject of study - Molecular kitchen as a professional chef.

Purpose of the study: To establish an experienced way of the relationship of chemical processes with technology for cooking dishes in molecular cooking.

In our work, we put forward a hypothesis:

Modern development of cooking is impossible without knowledge of chemistry and biology.

Research tasks:

Set the relationship of molecular cooking with chemistry.
Determine the features of molecular cooking, its advantages and disadvantages.
Implement the study of the relationship between chemistry, biology and cooking.
Determine the prospects for the development of molecular cuisine.

Research methods:

theoretical : analysis of scientific literature and information sources in the field of applied chemistry and catering technologies; Generalization and systematization of scientific facts.

Empirical : Questioning, research work.

1 Theoretical Aspects of Cooking Development
IN MODERN CONDITIONS

The relationship of molecular cooking with chemistry

I started my research with the survey of students of the II-III course of the Lyceum by profession "Cook, confectioner". 42 people took part in the survey. The following results were obtained.

Existence of molecular cooking?

4) In what conditions is it possible to prepare a dish of molecular kitchen?

Based on the data obtained, the following conclusions can be drawn.

Most respondents are confident that the modern cook should know the foundations of chemistry, since without it it is impossible to be a highly qualified specialist in its field of activity.

Also, ¾ respondents have an idea of \u200b\u200bthe molecular cooking and most of them received these knowledge in the lyceum, participating in extracurricular activities.

In the second subsection of its work, I looked at the features, the advantages of its features and disadvantages of molecular cooking.

Molecular kitchen, or molecular gastronomy - the direction of studies related to the study of physicochemical processes that occur when cooking. It studies mechanisms responsible for the transformation of ingredients during cooking food processing, as well as social, artistic and technical components of culinary and gastronomic phenomena in general (from a scientific point of view). it A thoughtful approach to cooking food based on modern knowledge, which gives us a fundamental science, summarizing various culinary phenomena, the origin in the history of cooking, plus modern innovative technologies.

As a result of working with various sources, I learned that there is an opinion: the molecular cooking was invented at all in the West, but in the Soviet Union.

Despite the fact that the molecular cooking is considered to be a new direction, but such people known for a long time ago, marshmallow, marshmallow, sugar, doctoral sausage and artificial caviar are preparing for the same technology.

In Russia, the molecular cuisine is engaged in the restaurant Anatoly Comm, which experiments with European culinary technologies at the original Russian dishes like borscht, herring under the fur coat and Borodino bread.

Examples of world gastronomic restaurants can be brought quite a few. The most famous - London "greasy duck", where the cook Heston Bluuma will dry guests with its own copyrighted dishes: liver with jasmine, banana with parsley and strawberry with candied celery.

Let's start with the fact that, when cooking, many of the operations used in chemistry are used: weighing, grinding, mixing, heating, dissolution, filtering. Equipment in chemistry and cooking also has similarities .____________

The main techniques of molecular cuisine:

processing products with liquid nitrogen,
emulsification (mixing insoluble substances),
spherification (creation of liquid spheres),
gelling
carbonization or enrichment of carbon dioxide (gas),
vacuum distillation (alcohol separation).

Chemicals are used for performing dishes in molecular cuisine:

Agar-Agar and Carrageenan - extracts of algae for cooking jelly,
Calcium chloride and sodium alginate convert fluids into balls like IKREA,
Egg powder (sepped protein) - creates a more dense structure than fresh protein,
Glucose - slows down crystallization and prevents liquid loss,
Lecithin - connects emulsions and stabilizes whipped foam,
Sodium citrate - does not allow particles of fat to connect.

In the second chapter of my work, I examined practical aspects
relationships of chemistry, biology and cooking

Results of my practical research I will demonstrate to you in the formtables "Relationship of chemical processes and technologies of cooking dishes"

1 To demonstrate experiments, I used one of the most used products in cooking: chicken protein .___________

2 During the second experience, I installed under what conditions faster and densely produced protein foam, which is important when preparing a row of dishes .______

3 In the third experience, we reviewed the interaction of carbonic salts

with stronger acids, such as acetic. Carbon dioxide released as a result of the reaction is also used in the preparation of flour confectionery products.

4 Molecular cooking and chemical and physical properties of substances, such as the experience of the "density tower"

Conclusion

After examining the theoretical and practical aspects of this topic, we did the following conclusions: it is safe to say that the hypothesis is confirmed completely, chemistry and cooking are an example of coordinated and friendly work.

Even the best and proven recipe does not guarantee that the result will be a great dish. Too many secondary factors affect the final product. In order to never be disappointing in their own culinary talents, it is enough to own basic knowledge in chemistry. Similarly, new culinary directions and trends begin in restaurants, they are interested in gourmets and chefs professionals, carefully developing every detail of the dish, inventing new, unusual taste combinations and combinations of products, experimenting with cooking technology - and as a result, these dishes are almost impossible to reproduce .

Gradually, these new ideas, technologies and methods penetrate the Kouli-Narial Books, recipes are adapted and taken to armared by the food industry - and, finally, new dishes appear on the shelves of grocery stores, as it happened with the dishes of "new cooking" or fusion style. And it is possible that after ten years, the technologies used in scientific gastronomy, like a quick frost in liquid nitrogen, will be used in the home kitchen.

It would seem that everything that you can have already prepared and tried, but cooking continues to develop. A molecular cooking, changing the consistency and the form of products beyond recognition, comes to change the style of Fusion in the "High Cooking". Analysis of chemical processes during the preparation of food and the use of new technologies spawned a direction that can be called molecular cooking.

Is there a connection between cooking and chemistry, or cooking products are obtained without applying chemicals

1) get acquainted with the term "cooking"; 2) Find information on how the chemistry "serves" cooking 3) shed light on the "food of the future" - "the latest technologies in our stomach" 4) make conclusions and conclusions.

Cooking (from Lat. Culina is a kitchen) - the art of cooking, as well as the collective name of the evios. According to legend, the Kulina was the servant and the assistant of the mythical healer of the Eskulap (patron of medicine) and his daughter Gigia (patronage of health). Cooking is the oldest industry of human activity. One of the first methods of thermal culinary processing was frying on open fire, in the ash and on hot stones, the cooking reflects the collective experience of the people and is therefore physiologically advisable, since food personifies an ancient connection connecting everything alive, including. and man, with its nature.

National cuisine of each people is an integral part of its material culture. Distinguish folk and professional cooking. The latter arose on the basis of the people who developed and improved cooking professionals. Professional cooking, on the one hand, art, and on the other - science based on the achievements of physics, chemistry, nutritional physiology and other industries. Culinary was carried away by many famous cultural figures: Leonardo da Vinci, S. Botticelli, A. Duma, V. Odoyevsky, etc. The founder of scientific culinary in Russia was D. Kanshin. After the emergence of mechanized enterprises of the appropriate nutrition, the cooking has become technical discipline - cooking technology.

With this most interesting question, we turned to our chemistry and ecology teacher, Korzhevian Oksana Vladimirovna, and received many answers. We chose the most, in our opinion important.

Selitre Selitra is used when meating and smoking meat products. First, it is a preservative, contributing to longer storage of the product. Secondly (and this is the main thing!), Helps the meat product after heat treatment to preserve more or less natural color: from deep red in solid steel sausages, to the appetizing pink in the hips. The nitrate should be special - food, with a high degree of purification, and not the one that is used in the manufacture of powder or explosive devices. It is important to abide by caution in the dosage. In large, quantities and food smelt can turn into a terrible poison. Do not think that in industrial enterprises, meat products are literally soaked in a saltter solution. Of course, in fact, everything is more complicated. Mixed meat in front of smoke is kept (marked slightly) in a solution with a more complex composition: with salt content, vinegar, spices and spices and p. An insignificant additive of this Selitra.

Sodium glutamine The correct name of the substance mentioned in the question is a mononium solochic acid salt. Glutamic acid is an organic substance. Some representatives of the vegetable world are mushrooms rich in proteins, also contain glutamic acid. By the way, it is this acid that individual mushrooms (after their preparation) are obliged to be weakly pronounced meat taste and the ability to improve. The taste of other dishes. Are you already starting to guess the appointment of additives? Yes, glutamine additives improve, reinforce the meat taste of meat-containing dishes and, can be said, give it to even those products, where meat and in the messenger was not. Herden or useful sodium glutamine? What is not useful is obvious. After all, it is not vitamin, not mineral salt with microelements useful for the body. He is a kind of cheating to improve the taste of the product. Sodium glutaminate provokes appetite, he is a kind of "drug": he ate something with glutamine, tasty, I also want the same, or something like that ... If you have a desire to try to apply glutaminat in your kitchen, one advice: Be sure to buy it only in stores, in the spices departments. In the market, you can safely buy greens, and falsifications are possible with white powder glutaminat.

Smoke fluids were delicious to eat at all times. But the main goal of the use of smoking products was not the uce of gourmet, but the desire to preserve the product. Over time, in case of and improving the means of conservation and the appearance of refrigerated techniques, the emphasis shifted. Of course, today smoking is used mainly to give the product of a certain taste. The performance people came up with ways to condensate fragrant smoke, because they contain moisture in the steam faction. (The nearest analogues of the condensation process are a degreasing of birch bark or, sorry, self-robbing.) The liquid condensate obtained from smoke, passing the appropriate cleaning, is suitable for use as a very concentrated natural flavor, giving dish with smoked smokyness. Comfortable liquids are now widely used in the food industry as One of the additions to meat minced meat for some sausages and sausages. Perhaps, in these cases, synthesized flavoring flavors are used with smoking taste? Modern Chemistry Almighty ...

Preparation of jam, jam and cooking computers Sulfiate whole fruit and berries, puree of them, juices and other products with sulfur arhydride - a more progressive processing method. It is not related to the need to receive sulfur anhydride and safely. In order for sulfted fruit products (mainly semi-finished products for jams, jams, jelly) were resistant to storage, technological instructions were established by permissible norms of the sulfur arhydride in them (% by weight). Four fruits and berries are sulphy in barrels, filling on 90% of their volume, then wechind, leaving an open pin hole in the upper bottom for fill with the hose of a working solution of a 1-2% concentration in an amount of no more than 10-15% (less often - 20%) mass of fruits, or inserted a sulfur arhydride in the barrels. A significant part of fruit semi-finished products (especially puree) is sulfted in large stationary basins, tanks with a capacity of 10-25-50 tons and more. Liquid sulfuric anhydride is used to fuse fruits instead of treating with sulfur gas.

Cooking that changes the consistency and the form of products to be unrecognizable no news. Egg with a protein inside and yolk outside, foamed meat with a garnish of foamed potatoes, jelly with the taste of marinated cucumbers and radish, crab syrup, thin plates of fresh milk, ice cream with a tobacco aroma exist not in fantastic novels, and already in our time. Perhaps food will be "digital", and the dishes will "download" from the Internet and "Print" on special "printers".

The food that expects us in the future on the shelves of supermarkets or on the tables of restaurants, externally will not differ from today's meal. However, it will be done, processed and prepared in a different way. Much more attractive will be "functional food" - products and drinks with the addition of vitamins, minerals, polyunsaturated ohome-3 fatty acids. Molecular cooking will make it possible to create fundamentally new types of food, connecting intact. Smells and tastes will appear, which the world did not know. In particular, the chemists and biologists of the Swiss perfume giant Givaudan, created over 20 thousand artificial flavors (300 only for one strawberry), organized an expedition to Madagascar's forests in search of molecules from which new smells can be extracted.

New products are ready to offer the Space. Space flight factors (weightlessness, crowding, difficulty heating) have strict nutritional requirements. But the most important requirement is to preserve the freshness and taste quality of products for weeks, and even months. As part of the American space agency NASA, Advance Food Technology has been working, which specializes in the preparation of food for space expeditions. In order to increase the shelf life of cosmic food, specialists carry out its processing of high pressure, pulsating electric field. In this way, a sandwich has already been prepared, edible even seven years old!

So, at the beginning of our study, we have been delivered by a hypothesis. At the end of the study, we can say with confidence that the hypothesis is confirmed completely, chemistry and cooking are an example of a well-coordinated and friendly "team". This "team" makes scientists strain the brain, and we are trying and trying increasingly complicated and more delicious products. But do not forget about the "harm" of chemistry - in large quantities, it can be destructive for "first-historians" - scientists, as well as for such consumers as we are with you. But real surprises are waiting for us ahead - recipes created as a result of molecular studies, genetic discoveries and space research. And it is possible that after ten years, the technologies used in scientific gastronomy, like a quick frost in liquid nitrogen, will be used in the home kitchen. Good luck to you - in culinary (and in others!) Affairs, and all - a pleasant appetite!

← + Ctrl + →

Basic chemical processes occurring in thermal culinary processing of products

The nature of the processes occurring during the thermal processing of plant and animal products differs significantly.

A distinctive feature of vegetable products is the high content of carbohydrates in them - over 70% of dry substances. The absolute majority of plant products used in human nutrition is parts of plants containing live parenchymal cells. They contain substances that are of interest in nutrition - mono- and oligoshara and starch. These cells have a primary shell consisting of low molecular weight cellulose and low molecular weight fractions of hemicellulose, the distinctive feature of which is the predominance between the structural units of the R-1,4-bond (this is important, since it is this connection that is not destroyed by the digestive enzymes of a person). In the median plate and interclausers are pectin substances. They are based on the residues of galacturonic acid, interconnected by A-1,4-bonds (this relationship is also not destroyed by human digestive enzymes). However, the degree of polymerization them, depending on the phase of the development of the living cell, can vary greatly: from 20 to 200 or more residues. With an increase in the degree of polymerization, the solubility of pectin substances and water decreases and mechanical strength increases. Thus, the washed "protopectin", with which the mechanical hardness of fruits, berries and vegetables is associated, is in reality high molecular weight pectin, which forms a "secondary" water binding, which, due to the special properties of the "related" "ODD and gives mechanical strength to plant products. At the same time, in all plants there are active pectinesterases and several less active polygalactures, which, in a certain period of life, plants are activated and begin to destroy the secondary structure of pectin to form low molecular weight pectins and water. In this case, the product is softened (this enzymatic process can occur during storage). Since the primary wall is easily permeable, and the secondary, and even more so tertiary, there are no walls in living cells, the low molecular weight pectin and water is partially moving into protoplasm of cells under the action of non-political enzymes.

When cooking under pressure when the temperature rises against the usual 2-3 s, the duration of cooking is reduced by about 1.5 times. Small pieces are heated (up to 70-80 ss in all volumes) are faster than large, but the extraction of water-soluble substances increases. Therefore, grinding cannot be very strong. Practice has the optimal size of the product and the duration of cooking.

Cooking products in leather (for example, potatoes in the peel, beets and carrots in the skin) is not reflected on the duration, but leads to a noticeable decrease in the loss of food substances, since the dense surface layer (epidermis, periderma) prevents extraction. Cooking on a pair also reduces the loss of food substances compared to cooking in water, since the extraction affects only the most surface layers.

With frying, there is mainly the thermal decomposition of the "secondary" structure of pectins to form soluble pectins and water. Starch grains and low molecular weight pectin begin to react with water, and they are partially moving to the gel-like state. However, if the evaporation of water from the product during frying occurs quite intensively, the gel dries up and the product becomes solid again - its mechanical strength increases several times. To reduce the evaporation of water, the fry is carried out in the presence of fat, which, enveloping the product, reduces the surface temperature and moisture evaporation rate. With frequent stirring, a crust is formed, also delaying evaporation, and the product becomes juicy.

You can fry at all in the layer of fat ("in the fryer"). In fact, this is not fry, but cooking in fat. In this case, the temperature of the medium is higher than with conventional cooking and softening occurs faster. There are few fat soluble substances in plant products, therefore, the loss of food substances in frying is insignificant, except, of course, disintegrated with vitamins.

In conclusion about the thermal processing of plant products containing a slight amount of pectin, but a lot of starch (grains, leguminous). Their processing is mainly in the combustionation of starch at elevated temperatures and in the presence of outer water. Therefore, only Cooking applies to them. The absorption of water with cessiercy starch reaches 100-200%,

In animal products of origin, proteins are most valuable in food and culinary terms (it is more correct to speak not "protein", but "proteins", i.e. there are many individual proteins that differ in composition and properties).

The mechanical strength of the meat product is due to a certain rigidity of the "tertiary" structure of white cubes of the greatest rigidity, proteins of connecting tissues (collagen and elastin) are provided. One of the main, but not the only factor that causes the stiffness of the "tertiary" structure of most protein of animal origin (exception - eggs, caviar) is the presence of water in them (in the form of "strength", "hydrate", etc., which are not considered here) . In meat products, water in the "tertiary structure is mainly associated with muscle dishes and not with connective tissues. The content from dinel-tanned proteins depends on the nature of the raw materials of animals and a number of other conditions.

The mechanical strength of meat products at the same time the temperature coagulation of proteins is noticeably reduced, depending on nature, starts from 60 ° C, and for most 70 ° C during cooking and roasting meat, the temperature inside the product depending on the type of meat and the cous k. Usually reaches 75 -95 ° C. However, to fry meat with a large number of connective tissues is not recommended as the water released when the "tertiary" structure of muscle proteins is destroyed, may not be enough for gelatinization (moreover, part of the water evaporates). Such a "housing" meat is better to cook or stew. Since the gelation of connective tissue proteins contributes to the acidic reaction of the medium, it is desirable to divert meat in acidic solutions (in vinegar, in dry wine) or extinguishing in the presence of vegetables containing organic acids (for example, tomatoes), or with tomato-paste - in these cases, the tissues are softened significantly faster. Mechanical destruction of connecting tissues gives the same effect.

With traditional frying meat products, despite the fact that fat is added, there is a rather intensive evaporation of water; The product during long fry simply dries and becomes more solid again. To reduce this undesirable process, it is recommended to first fry a piece of meat from different sides to the formation of a partially waterprooping crust (which is also a pleasant specific taste) or panicing it in flour or ground breadcrumbs. As a result, the humidity does not fall so sharply and the meat turns out more gentle.

Losses of foodstuffs in cooking occur due to partial inserting fat and extraction of a number of extractive components from tissues (nitrogen and bezazotic substances, minerals and vitamins). With frying losses result from the flipping of a large amount of fat, partial release of juice, thermal destruction of vitamins.

Oddly, at first glance, water losses occur not only during frying, but also during cooking, in water, and they reach noticeable values \u200b\u200b(compared to vegetation products) - on average from 30 to 50% depending on the type of meat. These losses occur due to the destruction of the "tertiary" structure of muscle proteins in their coagulation. At the same time, the "secondary" structure is not able to already retain a large amount of water, which is allocated together with water-soluble substances into external water.

Cooking under pressure by increasing the temperature speeds up gelatinization and reduces, thus, the time to obtain the finished product.

Some ideas about the magnitude of the loss of fixed nutrients with different methods of thermal culinary processing you will get, reading the table. 23.

If we summarize the thermal processing of food products, then you can draw the following conclusions.

The most rational in terms of the conservation of valuable foods by thermal processing are: for vegetable products - cooking without drag and cooking in the peel; For animals - quenching, baking, use of meat in the form of a kitlet, especially steam.

With any thermal processing, the most intensively destruction of vitamins, especially vitamin C.

What practical tips can be given a household to choose a method of heat treatment, what is better to cook, fry or stew?

It seems that for the preparation of everyday food it is necessary to use the most rational methods of thermal processing. At the same time, for snacks and side dishes more often serve greens, fresh vegetables and cabbage to compensate for the loss of vitamins occurring during thermal processing. The rational methods of thermal treatment are very useful and to those who need dieties of nutrition: there are no mechanical stimuli of the gastrointestinal tract in the products (fairy to kidney) at the same time completely abandoning the taste of their fried products for adults practically, healthy people would be wrong. But cooking is better to postpone until Sunday and festive days such a variety of nutrition can be a frame of data.

← + Ctrl + →
Homemade Food BasicsHomemade technology

Fig. 1.3.Starch grain structure:

1 - the structure of amylose; 2 - the structure of amylopectin; 3 - starch grains of raw potatoes; 4 - starch grains of boiled potatoes; 5 - starch grains in the cheese dough; 6 - Starch grains after baking

When heated from 55 to 80 ° C, the starch grains absorb a large amount of water, increase in volume several times, lose the crystalline structure, and therefore anisotropy. Starch suspension turns into a holter. The process of its formation is called melting. Thus, the challenization is the destruction of the native structure of starch grain, accompanied by swelling.

Temperature in which the anisotropy of most grains is destroyed, is called temperature claystherization. Clasting temperature of different types of starch Nonodynakova. Thus, the cooling of potato starch occurs at 55-65 ° C, wheat - at 60-80, corn - at 60-71 °, rice - at 70-80 ° C.

The process of brassyrization of starch grains is stages:

* at 55-70 ° C of grains increase in volume several times, they lose optical anisotropy, but still retain a layered structure; In the center of the starch grain, the cavity is formed ("bubble"); The suspension of grains in water turns into a honesty - a small-concentrated sol of amylose, in which the swollen grains are distributed (the first stage of the brassierization);

* When heated above 70 ° C, in the presence of a significant amount of water, the starch grains increase in the volume of tens of times, the layered structure disappears, the viscosity of the system (the second stage of the braiding) is significantly increased; At this stage, the amount of soluble amylose; The solution partially remains in the grain, and partially diffuses into the environment.

With long-term heating with an excess of water, starch bubbles are bursting, and the viscosity of the chainer is reduced. An example of this in culinary practice is the dilution of the jile as a result of excessive heating.

Starchs of tuber plant (potatoes, Topinamburg) gives transparent hollows of a jelly-like consistency, and grain (corn, rice, wheat, etc.) - opaque, milky-white, pasty consistency.

Claystaper consistency depends on the amount of starch: when it is kept from 2 to 5%, the hubber is obtained by liquid (liquid kisins, sauces, soups - mashed potatoes); at 6-8% - dense (thick kisins). Even more thick, the kleuter is formed inside potato cells, in porridge, pasta dishes.

Not only the concentration of starch is affected on the viscosity of the celature, but also the presence of various nutrients (sugars, mineral elements, acids, proteins, etc.). Thus, sucrose increases the viscosity of the system, the salt reduces, the proteins have a stabilizing effect on starch celars.

When cooling the starch-containing products, the amount of soluble amylose in them is reduced as a result of retrogradation (precipitation). In this case, there are aging of starch students (synerresis), and products are worn. The rate of aging depends on the type of products, their humidity and storage temperature. The higher the humidity of the dish, culinary product, the more intense the amount of water-soluble substances is reduced in it. The most quickly aging flows in a millet caress, slower - in manna and buckwheat. Increased temperature slows down the retrogradation process, so dishes from cereals and pasta, which are stored on marmiths with a temperature of 70-80 ° C, have good organoleptic indicators for 4 hours.

Hydrolysis starch. Starch polysaccharides are able to disintegrate to the molecules of their sugars. This process is called hydrolyolism, as it comes with the addition of water. Distinguish enzymatic and acid hydrolysis.

Enzymes, splitting starch, are called amilas. There are two types of them:

α-amylase, which causes a partial decay of circuits of starch polysaccharides to form low molecular weight compounds - dextrins; With prolonged hydrolysis, maltose and glucose is possible;

β-amylase that splits starch to maltose.

Enzymatic hydrolysis of starch occurs when making yeast dough and baking products from it, potato cooking, etc. In wheat flour, it is usually contained β-amylase; Maltose, which is formed under its influence is a nutritious environment for yeast. In the flour from the sprouted grain, α-amylase prevails, the decrees resulting under its effects give the products of stickiness, an unpleasant taste.

The degree of hydrolysis of starch under action)