Fortification of food. Currently, catering establishments quite widely use the method of artificial fortification of ready-made food. The organization of this work is entrusted to managers and catering workers, and control over the correct fortification of food is carried out by state sanitary and epidemiological supervision bodies. Particular attention is paid to fortifying food in nurseries, kindergartens, boarding schools, vocational schools, hospitals, and sanatoriums.

Ready-made first and third courses are enriched with ascorbic acid before serving food at the following rate: for children from 1 to 6 years old - 40 mg; from 6 to 12 years - 50 mg; for children and adolescents aged 12 to 17 years - 70 mg; for adults - 80 mg; for pregnant women - 100 mg and lactating women - 120 mg.

Ascorbic acid is introduced into dishes in the form of powder or tablets, previously dissolved in a small amount of food. Enrichment of food with vitamins C, B, PP is organized in canteens for workers of some chemical enterprises in order to prevent diseases associated with production hazards. An aqueous solution of these vitamins, 4 ml per serving, is added daily to prepared food.

Main food groups for fortification with vitamins:

1. Flour and bakery products – B vitamins;

2. Baby food products – all vitamins;

3. Drinks, including dry concentrates - all vitamins except A, D;

4. Dairy products – vitamins A, D, E, C;

5. Margarine, mayonnaise – vitamins A, D, E;

6. Fruit juices - all vitamins except A, D.

Preservation of vitamins

During storage and culinary processing of food products, some vitamins are destroyed, especially vitamin C. Negative factors that reduce the C-vitamin activity of vegetables and fruits are: sunlight, air oxygen, high temperature, alkaline environment, high air humidity and water in which the vitamin dissolves well. Enzymes contained in food products accelerate the process of its destruction.

Vegetables and fruits must be supplied to catering establishments of high quality in accordance with the requirements of current GOSTs, which guarantees their full nutritional value.

When storing vegetables and fruits in warehouses, it is necessary to maintain a certain regime: air temperature is above 3°C, relative humidity is 85-95%. Warehouses must be well ventilated and not have daylight. It is necessary to strictly observe the shelf life of vegetables and fruits.

During mechanical cooking, long-term storage and soaking of peeled vegetables and fruits in water is unacceptable, since vitamin C oxidizes and dissolves. When cooking, vegetables and fruits should be completely immersed in boiling water or broth. They need to be cooked with the lid closed, boiling evenly, avoiding overcooking. For salads and vinaigrettes, it is recommended to cook vegetables unpeeled, thereby reducing the loss of vitamin C and other nutrients.

Vitamin C is greatly destroyed during the preparation of vegetable purees, cutlets, casseroles, stews, and only slightly when frying vegetables in fat. Secondary heating of vegetable dishes and their contact with oxidizing parts of technological equipment lead to the complete destruction of this vitamin. In order to preserve vitamin C, the terms, conditions of storage and sale of ready-made vegetable and fruit dishes should be strictly observed. The shelf life of hot dishes should not exceed 1-3 hours at a temperature of 65-75°C, cold dishes - 6-12 hours at a temperature of 7-14°C.

B vitamins are largely preserved during cooking.

How to preserve vitamin C during heat treatment?

But it should be remembered that an alkaline environment destroys these vitamins, and therefore you should not add baking soda when cooking legumes.

To improve the digestibility of carotene, it is necessary to consume all orange-red vegetables (carrots, tomatoes) with fat (sour cream, vegetable oil, milk sauce), and add them sautéed to soups and other dishes.

The influence of vitamins, as well as minerals, as protective agents against environmental poisons, cardiovascular diseases and cancer is constantly debated. Some vitamins and minerals have the ability to bind harmful substances called free radicals, and thus prevent these pests from attacking and destroying our cells. We are talking about certain oxygen molecules. The destruction process caused by oxygen is also called oxidation (binding of elements or their compounds with oxygen). An example of such processes is corrosion or darkening of cut apples. In the body, the visible expression of cellular changes caused by oxidation can be called age spots or wrinkles.

Numerous oxidation processes take place inside our body. Excess free radicals, which can result from, for example, smoking cigarettes, ultraviolet radiation, air pollution, medications, certain foods or stress, cause long-term damage to our bodies.

By limiting such hazards, most radicals can be avoided. But often these precautions are not enough.

Therefore, it is necessary to fight harmful radicals, so to speak, from the inside. Antioxidants that prevent the oxidation process include, among other things, vitamins A, C, E and the trace element selenium. These substances can significantly protect our cells from attack by free radicals. This has given them increasing importance in recent years. Depending on ozone and environmental loads, solar radiation and nicotine intake, supplemental antioxidant intake is recommended.

Cooking Beef Properly

Not every housewife is able to deliciously cook the most difficult, and sometimes “difficult” meat - beef. The very first experiences of housewives in preparing this meat, according to statistics, lead to disappointment.

Preservation of vitamins during cooking

This is one of the reasons for preferring pork, which is much easier to cook than beef. However, you cannot completely abandon it, since beef contains many more useful substances that are very necessary for the human body than pork. So how should you cook beef?

Basic rules for cooking beef

• Do not marinate beef with vinegar, as this will make it tough and tasteless. To marinade this meat, you can use semi-dry or dry red wine with the addition of finely grated two onions and a couple of bay leaves.
• For stewing, the back of the shank or shoulder is better suited, for chops and frying - tenderloin.
• Fat that is yellow or dark in color indicates that the meat is too old.
• Before cooking, it is recommended to pound each piece of beef for 1-2 minutes.
• When frying, you should first brown the beef over high heat on both sides, as a result the juice will not evaporate or flow out, and this ultimately indicates the juiciness of the beef.
• It is not recommended to add cold water during frying, otherwise the meat will be tough; boiling water should be added.
• If you add lime, lemon or pineapple juice during frying, the beef will become soft and very tasty.
• Beef should be cut across the grain, as a result it will be juicy during and after cooking.
• It is always recommended to fry beef meat with a lid.

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How to Preserve Vitamin C in Foods

Ascorbic acid (vitamin C) is one of the most important micronutrients - nutrients that are found in our body in very small quantities, but their role is very high.

It is not synthesized in the human body (unlike most mammals), and therefore must be supplied with food, since it is a regulator of many biochemical reactions and protective mechanisms.

Vitamin C is extremely unstable in the external environment and is quickly destroyed when heated. For example, when boiling vegetables or fruits or preparing first courses, it is destroyed almost completely in just 2-3 minutes. In addition, the metal surface of dishes and household appliances contributes to the destruction of vitamin C. When calculating nutritional status, it is generally accepted that culinary losses of vitamin C are equal to 50%. Despite the fact that quick freezing does not significantly affect the amount of ascorbic acid in products, its preservation will depend on the conditions of further defrosting and cooking. When storing apples, potatoes, cabbage and other vegetables and fruits, vitamin C is noticeably destroyed and after 4-5 months of storage (even under proper conditions) its content drops by 60-80%.

Ascorbic acid is well absorbed in the small intestine and from there enters the blood, where it circulates freely and is distributed throughout all organs and tissues. In the human body, vitamin C is involved in many biochemical reactions, for example, in the synthesis of collagen, the main structural protein of connective tissue, which ensures the functionality and stability of blood vessels, bones, and tendons.

How to preserve vitamins when cooking

Vitamin C plays an important role in the synthesis of neurotransmitters - norepinephrine, serotonin, as well as bile acids from cholesterol, which some experts try to explain the beneficial effect of vitamin C on its metabolism.

Vitamin C is an antioxidant; it provides direct protection of proteins, fats, DNA and RNA of cells from the damaging effects of free radicals, which are often formed in cells during life. Ascorbic acid maintains the level of reduced glutathione, which itself is the body's leading antioxidant, providing protection against free radicals, toxins, and heavy metals at the biochemical level. In addition, vitamin C has a significant effect on the metabolism of other micronutrients and vitamins.

Ascorbic acid enters the human body mainly from plant foods. When consumed in the proper quantities, the amount of vitamin C will meet the physiological needs of a healthy person or even exceed them (which is okay, the body will excrete excess vitamin C in the urine). However, this is not usually the case; vitamin C deficiency is the most common vitamin deficiency. This is due to two main problems: a decrease in the consumption of fresh vegetables and fruits and a high degree of technological processing of food in which certain parts of plants are used. The fact is that the content of vitamin C in different parts of the fruit is not the same - it accumulates in the peel, outer layers, and leaves more than in the pulp, petiole, and stem.

Foods rich in vitamin C:

rosehip, sweet pepper,

currants, sea buckthorn,

parsley dill,

Brussels sprouts, white or cauliflower,

potatoes, tomatoes,

apples, pineapples, citrus fruits.

Some foods contain a special enzyme, ascorbate oxidase, an anti-vitamin that interferes with the absorption of vitamin C. It is found in significant quantities in zucchini and cucumbers, however, heat treatment (for example, baking) inactivates this enzyme.

The physiological need for vitamin C for an adult is an average of 90 mg per day. This amount is contained in 225 grams of lemon or just 45 grams of black currants. The real need for vitamin C in modern life is much higher than this level, which is why additionally fortified foods and dishes are so important. You can find out about this by carefully studying the product label. They are usually enriched with fruit, berry and vegetable juices, liquid dairy products, and canned food. Additional C-vitaminization is required when organizing meals in children's institutions, hospitals, and sanatoriums.

Additional amounts of vitamin C are necessary during pregnancy, lactation, when living in cold climates, when working in production with hazardous working conditions, and with additional foreign chemical load (for example, smoking).

A complete lack of vitamin C leads to the development of scurvy. This condition was described many centuries ago in people who made long journeys (sailors) and completely excluded plant foods from their diet. Symptoms of scurvy include loss of strength, bleeding, hair and tooth loss, pain and swelling in the joints. Scurvy, if left untreated, leads to death.

A simple vitamin C deficiency will be indicated by bleeding gums when brushing your teeth. In this case, other causes should be excluded (gum disease, incorrect selection of brushes, etc.).

Hypervitaminosis of vitamin C has not been described (we have already said that excess vitamin C is excreted in the urine). However, excessive consumption of vitamin C (usually from pharmaceutical preparations) can provoke a severe allergic reaction and kidney problems. A healthy person cannot have excess vitamin C from food.

Now it is clear how important ascorbic acid is and that its main source should be natural products. For information about what other vitamins are found in various foods, see our article on vitamins.

First, it is worth remembering that vitamin C breaks down at high temperatures, especially when cooked. Interestingly, when oxygen is available, the loss of vitamin C is twice as great as when the product was prepared without oxygen (in a pressure cooker).

Secondly, it is also known that the longer a product is cooked, the greater the loss of vitamin, so the products should be placed in boiling water.

Thirdly, in an alkaline environment, vitamin C is destroyed faster than in an acidic environment. Therefore, when cooking vegetables, add a little acetic acid. Vitamin C is preserved well when salted and pickled.

Fourthly, do not use iron or copper utensils, spoons or ladle when cooking. We have already said that metal utensils contribute to the destruction of vitamin C.

And the most important and reliable means of preserving ascorbic acid remains the way of eating vegetables and fruits fresh and raw! Bon appetit!

The article was prepared on the basis of information from open sources.

Is the “third step”, the refusal to cook food over fire, really so important? Was it in vain that the hero Prometheus suffered for stealing fire from the gods in order to benefit humanity? And don’t the Olympian gods still punish people for acquiring obviously stolen goods?

But let’s first ask ourselves a simpler question: what kind of eagle pecked at our hero’s liver? Maybe this is just a beautiful fairy tale, and the sad prose is that during the day Prometheus fried meat on the fire, and, as you know, fried meat hurts the liver? This is the “eagle” that tormented his liver during the day! During the night the pain subsided, and in the morning our hero fried a new piece of meat on the fire... It’s delicious!

Although modern nutritional science recognizes the processing of food over fire as normal and even absolutely necessary, as well as in various other ways that significantly worsen its nutritional properties, calls to at least slightly spare food during processing are becoming louder. Here, for example, is a small quote from an article signed by V. Timakov, President of the Academy of Medical Sciences, and A. Pokrovsky, Director of the Institute of Nutrition:

“Particularly careful handling requires biologically valuable substances contained in food products - proteins, vitamins, polyunsaturated fatty acids, minerals. Therefore, it is necessary to use the most gentle methods of technological processing and preservation of products...”

When raw foodists read such instructions in the newspaper, they, of course, only smile, since they have been following them for a long time and most diligently, and the most “natural” raw foodists do not process food in any way, or even chop vegetables. Washed and ate. There is nowhere to go further... They reason “simply, like men”: if any of the so-called “food products” in raw form cannot be taken into the mouth, then it is most likely not human food. That’s why you have to boil, fry, season with sauces and side dishes to make it edible.

The human body cannot protect itself from cooked food, but reacts to it. “New discoveries of biophysics and biochemistry,” writes the Bulgarian professor T. Todorov, “confirmed the correctness of the theoretical premises of a raw food diet. Thus, the Soviet scientist, bacteriologist Kushakov, observing scurvy during a long stay in the Arctic regions, discovered that raw plant food prevents food leukocytosis (considered formerly a physiological phenomenon), which almost always occurs when cooked food touches the palate. This leukocytosis is expressed in the fact that white blood cells quickly concentrate in the walls of the intestines, as if preparing to meet an infection.

This mobilization lasts 1-1.5 hours and then stops, but when repeated many times every day, it causes exhaustion of the body, and, in addition, the white blood cells do not perform their other protective functions. This leukocytosis can be prevented by eating raw plant foods or taking large amounts of such food before eating cooked food... Industrialization and urbanization, continues T. Todorov, are increasingly covering all developed countries. The second half of the population of these states—women—is also involved in industrial, scientific, cultural and social life. For this reason, as well as for convenience and commercial purposes, industrial food production is now increasingly developing. All this alienates modern man from nature and healthy food. And despite the great successes of medicine, the so-called “diseases of civilization” have appeared and are developing on an enormous scale. It is no coincidence that the Executive Committee of the World Health Organization called them “the largest epidemic of humanity.”

The experiment on rats, which is described in the Fundamentals of Medical Nutrition by Professor M.I. Pevzner, is very indicative.

How to Preserve Vitamin C in Vegetables

Rats, as is known, are able, even without laboratory tests, to find exactly those products from cash that they need - for example, they compensate for an artificially created deficiency in them in a certain microelement.

“Experiments, for example, on rats have shown the following: if you take two groups of rats and give one of them only raw eggs, and the other - hard-boiled eggs, then those rats that feed exclusively on raw eggs remain alive, and those that feed on hard-boiled eggs ", after some time they die. If one group of rats is given daily the same amount of both hard-boiled and raw eggs, then the rats eat only hard-boiled eggs, without touching the raw ones, and after a while they die."

Pevzner cites this experience as proof of his position that our regulators (appetite, thirst, feeling of fullness) do not always show us the right path in nutrition. I think that this experience clearly speaks about something else: boiled food is a human invention against which nature has not provided any protection, since boiled food has never existed in nature.

To eat means to get fat >>>>

Changing vitamins

Carotene is the most resistant to elevated temperatures. B vitamins are partially transferred to the decoction and partially destroyed. Vitamin B6 is destroyed to the greatest extent: when spinach is cooked, its content in the product decreases by 40%, white cabbage - by ~ 36, carrots - by 22, when potatoes are boiled and fried - by 27...28%. Thiamine and riboflavin are lost somewhat less during cooking - about 20%; approximately 2/5 of the vitamins of this group preserved in vegetables are transferred into the decoction.

Vitamin C undergoes significant changes, which partially turns into a decoction and is partially destroyed.

Lecture No. 15 Changes in vitamins during cooking

Vitamin C at the beginning of heat treatment of vegetables and fruits is oxidized under the influence of atmospheric oxygen with the participation of oxidative enzymes. As a result, part of the ascorbic acid is converted into dehydroascorbic acid. With a further increase in temperature, thermal degradation of both forms of pitamine C occurs.

Ascorbigen can be hydrolyzed to release free ascorbic acid, which can also undergo oxidation and thermal degradation.

The degree of destruction of vitamin C during thermal cooking of vegetables and fruits depends on many factors: the properties of the semi-finished product being processed, the rate of heating of the product, the duration of processing, contact with atmospheric oxygen, the composition and pH of the environment, etc.

Thus, when boiled in water, the degree of destruction of vitamin C in potatoes can vary widely depending on its content and the ratio of reduced and oxidized forms of ascorbic acid. For example, when cooking unpeeled potatoes in the autumn, the degree of destruction of vitamin C in it does not exceed 10%, in the spring it reaches 25%. In peeled potatoes, 15...35% of vitamin C is destroyed in the fall, and more than half in the spring. When cooking white cabbage (variety Podarok), the loss of vitamin C in the fall amounted to 2...3% of its initial content, in the spring - 30%. Thus, the higher the vitamin C content and the less dehydroascorbic acid in vegetables, the less it is destroyed.

However, when cooking some other varieties of cabbage (Amager, Belorusskaya, Slava), the loss of ascorbic acid in autumn and spring is approximately the same or less in spring than in autumn. In addition, there is evidence that when some vegetables (tomatoes, Brussels sprouts, kohlrabi) are cooked, vitamin C is practically not destroyed.

The faster potatoes, vegetables and fruits are heated during cooking, the less ascorbic acid is destroyed. For example, when boiling potatoes by immersion in cold water, 35% of vitamin C is destroyed, while in hot water - only 7%. By accelerating the heating of vegetables, the enzymes that convert ascorbic acid into dehydroform are inactivated, as a result of which vitamin C is better preserved.

The shelf life of vitamin C is inversely related to the duration of exposure to high temperatures on the product. Heat cooking vegetables and fruits for a longer time than required to bring them to readiness can lead to unnecessary loss of vitamin C.

The presence of oxygen promotes the oxidation of vitamin C and its further destruction.

Various substances contained in the cooking medium can accelerate the destruction of ascorbic acid or contribute to its preservation. Ions of copper, iron, manganese, contained in tap water or entering the cooking medium from the walls of dishes and equipment, catalyze the destruction of vitamin C. Copper ions have the greatest catalytic effect. Iron and manganese contribute to the destruction of vitamin C to a much lesser extent, although iron can enhance the catalytic effect of copper, which depends on the reaction of the environment. In an acidic environment it manifests itself to a lesser extent. Thus, when heating solutions of ascorbic acid at pH 5, 64% of vitamin C is destroyed, and at pH 3 - only 9.3%. When cooking vegetables in an acidic environment (for example, when adding tomato paste, pickled cucumbers, etc.) to soups, vitamin C is better preserved, which is apparently due to the weakening of the effect of copper ions.

Some substances contained in food products have a protective effect against vitamin C. The degree of destruction of ascorbic acid in vegetables during heat treatment is always less than when heating its solutions of the same concentration. It is believed that amino acids, starch, vitamins (A, E, thiamine), pigments (anthocyanins, flavones, carotenoids) and other substances to one degree or another protect vitamin C from destruction. For example, when boiling potatoes in meat broth containing amino acids, vitamin C is almost completely preserved, while when boiling in water, its loss is about 30%.

Destruction of ascorbic acid can also occur during long-term storage of boiled vegetables, both hot and at room temperature or in a refrigerator. Within 3 hours of storing boiled vegetables in a cooled state, up to 20...30% of vitamin C can be destroyed, and after 24 hours of storage, only about half of its original content remains in vegetables.

During hydrothermal processing of vegetables and fruits, ascorbic acid, as a water-soluble vitamin, is partially converted into a decoction or condensate (during steaming), and therefore even less of it remains in the product. For example, when cooking white cabbage, more than 40% of ascorbic acid goes into the decoction, while in potatoes - 10...20%.

The total loss of vitamin C in potatoes, vegetables and fruits depends on the method of thermal cooking. The greatest losses are observed when cooking in water. Steaming helps preserve vitamin C. Thus, when boiling whole peeled potato tubers in water, the loss of vitamin C is 49%, when steaming - 38%.

When vegetables are poached, vitamin C is destroyed somewhat more than when they are boiled. For example, when cooking white cabbage, the total loss of vitamin C was 60%; when poaching, it was 66%, since in this case the product is partially in a steam-air environment containing oxygen.

When processing vegetables in microwave devices, the shelf life of vitamin C increases by 20...25% compared to boiling and baking.

Starting, which is explained by the relatively quick heating of vegetables and the reduction in the duration of heat treatment.

In the process of frying potatoes and vegetables, vitamin C is destroyed to a lesser extent than during hydrothermal treatment, since fat, enveloping pieces of vegetables, protects them from contact with air oxygen.

In the manufacture of products from cutlet mass (cutlets, zrazy, croquettes, casseroles), when heat exposure alternates with mechanical processing, the loss of vitamin C reaches 90% or more. To preserve as much vitamin C as possible in vegetable dishes, it is necessary to strictly adhere to the technological regime, which helps stabilize ascorbic acid:

v ensure rapid heating of potatoes and vegetables during thermal cooking;

v cook vegetables and potatoes in water at a moderate boil and do not allow the liquid to boil;

v do not exceed the terms of thermal cooking provided for bringing potatoes and vegetables to readiness;

v use decoctions of peeled potatoes and vegetables to prepare soups and sauces;

v do not allow long-term storage of finished potato and vegetable products.

Test questions and assignments

1. What physical and chemical processes occurring in potatoes, vegetables and fruits cause the softening of their tissues during heat treatment?

2. What factors influence the duration of thermal cooking of potatoes and vegetables?

3. What does the nutritional value of potatoes and vegetables depend on during mechanical and thermal cooking?

4. Why do peeled (cut) potatoes and apples darken when stored in air? What processing methods are used to prevent browning of these products?

5. What is the reason for the change in color of vegetables, fruits and berries with a red-violet color of the pulp during heat treatment? Name the technological methods used to preserve color.

6. Why do green vegetables turn brown during cooking? List the technological methods used to preserve color.

7. How does culinary processing of potatoes, vegetables and fruits affect the preservation of various vitamins in them? What technological methods are used to preserve vitamins?

Choose three correct answers. To preserve vitamins in food products, use:

1) quick freezing

2) canning with sterilization

3) drying in the sun

4) vacuum drying

5) pickling

6) pasteurization

Explanation.

To preserve vitamins in food products that have been cooked or stored, the following conditions must be met:

1. Store food in a dark and cool place.

2. Do not carry out primary processing of food products under a brightly burning lamp.

3. Wash food products whole or in large pieces, cut them immediately before cooking.

4. Do not drain the water in which legumes or cereals were soaked, but use it when cooking them.

5. Prepared vegetables should be cooked immediately. If you need to store peeled vegetables, place them in a cool place for no more than 3-5 hours.

6. To cook, place vegetables and fruits in boiling water.

7. Strictly observe the heat treatment time, avoid overheating.

8. Close the container in which the heat treatment is carried out tightly.

9. Minimize stirring of food when heating.

10. Use more widely those types of culinary processing that do not require prolonged heating (it is better to boil vegetables and potatoes in their skins or whole).

11. Raw vegetables, fruits and berries should be a necessary part of the daily diet. Cut and grate vegetables, mix them and season with mayonnaise, vegetable oil or sour cream only before use.

12. Store pickled and salted vegetables under a load covered with brine. There is no need to rinse sauerkraut, as more than 50% of vitamin C is lost.

13. Use vegetable broths to make soups and sauces.

14. Store hot ready-made vegetable dishes for no more than 1 hour; their shelf life should be minimal.

15. For vegetable decoctions, sauces, gravies and soups, it is advisable to use some leftover vegetables rich in vitamins, minerals and flavors (for example, cabbage stalks, parsley and early beet tops, dill stems).

16. To increase the vitamin value of food in the diet, it is advisable to include drinks from dried rose hips, wheat bran (rich in B vitamins), dried apples and other fruits and vegetables).

17. It is also important not to leave food in water for a long time.

Various factors - boiling, freezing, drying, lighting and many others have different effects on different groups of vitamins. The least stable of all vitamins is vitamin C, which begins to break down when heated to 60°C. Access to air, sunlight, and increased humidity contribute. destruction of this vitamin. Vitamin A is more resistant to high temperatures, but is easily oxidized when exposed to air. Long-term storage and drying have a detrimental effect on vitamins A and C, but do not destroy vitamins D, E, B1, B2.

The pages of cookbooks focus mainly on the taste and appearance of ready-made dishes, but not a word is said about the chemical composition of food products. But even if the dish looks appetizing, if certain rules for preserving nutrients are not followed, it will not bring any benefit to a person. What tricks should a real housewife know in order to prepare both healthy and appetizing food?

The main task of the housewife is to preserve vitamins in products during cooking and storage. Nutrients are preserved only with gentle processing, which does not require long heating processes, otherwise you can lose from 10 to 15% of biologically active substances.

Rules for defrosting food

• Thawed fish and meat should be subjected to immediate heat treatment, which will preserve the essential vitamins included in their composition;
• Food products after defrosting should not be frozen again, as after this they will lose almost all nutrients and lose their taste;
• Meat products should be cooked only after complete defrosting. Otherwise, the loss of vitamins and minerals included in their composition is ensured;
• When defrosting food, you should not lose sight of the fact that rapid defrosting leads to the loss of biologically active substances. This is why it is necessary that they are thawed at room temperature;
• If frozen foods are defrosted in water, there is a significant loss of basic food ingredients, which is accompanied by intensive proliferation of microorganisms.

Heat treatment rules

Heat treatment contributes to the violation of the biological value of food, the structure of their tissues, biochemical bonds, and also reduces the amount of minerals, enzymes and vitamins included in the composition. As a result of such changes, food loses its properties, as it becomes less useful for the human body.

When frying, strong heating of fats occurs, which has a depressing effect on the biological and nutritional value of the processed product. These are not all the disadvantages of this treatment, since frying promotes the production of carcinogenic substances that negatively affect human internal organs, causing various diseases. This type of culinary processing is the most imperfect and “old-fashioned”, as it contributes to the loss of the nutritional value of food and only brings harm to the human body.

During cooking, much less biologically active substances are lost and microbes are destroyed under the influence of high temperatures. Food prepared in this way has a more natural taste and is better absorbed by the body. When steamed, almost all vitamins are also preserved, which can only be compared with baking. This type of heat treatment can also be called gentle, since during its implementation there is practically no change in the chemical composition of food products.

• When cooking, use a minimal amount of water so that the food is only lightly covered. It is preferable to steam vegetables, as some vitamins are lost during cooking;
• Legumes should be soaked for some time before cooking, which will reduce cooking time. The product must be boiled in the same water in which it was kept for several hours;
• Cereals must be cooked in strict proportions of 1:2, since during heat treatment some of the vitamins go into the water and it is irrational to drain it;
• Whole cooked vegetables allow you to preserve almost all vitamins, and when preparing puree, about 20% of biologically active substances are lost;
• To retain the nutrients in foods, they should be placed in hot water or placed on a preheated baking sheet. It is also more advisable to prepare foods unpeeled and uncut, that is, whole and with peel;
• Food should be cooked only in enamel dishes, since any metal can cause a change in the chemical composition;
• The jam should be cooked for no more than 5 minutes, the so-called “five-minute”, which allows you to preserve nutrients and enjoy this product in the winter.

Currently, it is most rational to cook food in a slow cooker, since this method is the most gentle heat treatment, in which there is practically no change in the chemical composition of nutrients. In a slow cooker you can preserve almost all vitamins and minerals in their original quantities.

Reaction of food components to heat treatment

Housewives who want to preserve maximum benefits in products during culinary processing should know not only their composition, but also how vitamins react to various cooking methods. Different groups of nutrients are affected differently by boiling, frying, cooking and thawing.

Ascorbic acid is the most unstable element, which is destroyed already at 60°C. This vitamin is negatively affected by sunlight, long-term storage and high humidity. You cannot make jam from berries and fruits that contain this element, since the finished product will bring little benefit. Vitamin A is stable at high temperatures, but oxidizes at room temperature and is not affected by ultraviolet rays.

Chicken legs in a slow cooker

Vitamin D does not change when boiled in an acidic environment, but is destroyed in an alkaline environment. B vitamins are practically unchanged by cooking. These elements can only be destroyed by prolonged boiling. Therefore, products containing them should be cooked over moderate heat for a certain time.

Vitamin E can be heat treated for any time at any temperature, since this element is resistant to heat. Vitamins PP, A and D are preserved almost completely during cooking and baking, so the fruits and berries that contain them in compote are simply irreplaceable. Jam made from these products, rich in heat-resistant elements, helps replenish the vitamins a person lacks throughout the winter.

The film of fat promotes the preservation of nutrients, which, even during frying, allows you to retain some of the vitamins and minerals in food. Sugar also has a stabilizing effect, which is why jam is rich in basic food ingredients.

Despite the fact that jam allows you to preserve vitamins in berries and fruits for a long time, today freezing these products is more popular. By freezing, you can preserve not only vitamins A, D and PP, but also ascorbic acid in the original quantity.

There is practically no product in nature that contains all the vitamins in quantities sufficient to meet the needs of the body of an adult and a child. Therefore, maximum variety of the menu is necessary: ​​along with animal products and grains, there should be vegetables and fruits, including raw ones. To preserve vitamins in food products that have been cooked or stored, the following conditions must be met:

1. Store food in a dark and cool place;

2. Do not carry out primary processing of food products under a brightly burning lamp;

3. Wash food products whole or in large pieces, cut them immediately before cooking;

4. Do not drain the water in which legumes or cereals were soaked, but use it when boiling them;

5. Prepared vegetables should be cooked immediately. If it is necessary to store peeled vegetables, place them in a cool place for no more than 3 - 5 hours;

6. To cook vegetables and fruits, place them in boiling water;

7. Strictly observe the heat treatment time, avoid overheating;

8. Close the container in which the heat treatment is carried out tightly;

9. Minimize stirring of food when heating;

10. Use more widely those types of culinary processing that do not require prolonged heating (it is better to cook vegetables and potatoes in their skins or whole);

11. Raw vegetables, fruits and berries should be a necessary part of the daily diet. Cut and grate vegetables, mix them and season with mayonnaise, vegetable oil or sour cream only before use;

12. Store pickled and salted vegetables under a load covered with brine. There is no need to rinse sauerkraut, as this will lose more than 50% of vitamin C;

13. Use vegetable broths to prepare soups and sauces;

14. Store hot ready-made vegetable dishes for no more than 1 hour, the period for their sale should be minimal;

15. For vegetable decoctions, sauces, gravies and soups, it is advisable to use some leftover vegetables rich in vitamins, minerals and flavors (for example, cabbage stalks, parsley and early beet tops, dill stems);

16. To increase the vitamin value of food in the diet, it is advisable to include drinks from dried rose hips, wheat bran (rich in B vitamins), dried apples and other fruits and vegetables);

17. It is also important not to leave food in water for a long time;

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Vitamin C (ascorbic acid) is easily destroyed by heating, exposure to atmospheric oxygen and sunlight, and long-term storage. Even with proper cooking, 50-60% of vitamin C is lost, and when preparing vegetable casseroles, purees, cutlets - 75-90%. Storing vegetables and fruits in warmth and light accelerates the loss of vitamin C. With loss of moisture, the loss of water-soluble vitamin C increases. Based on these considerations, the following are recommended: rules when preserving and processing food products:

Vegetables should be stored in a cool place at a temperature of 2-4 ° C and air humidity of 85%.

It is necessary to prevent injury to vegetables during transportation and storage (so as not to contribute to their spoilage and increase the activity of oxidative processes)

When soaking vegetables after cleaning, use slightly salted water. This reduces the dissolved oxygen content in the water. The duration of keeping them in water should not exceed 10-15 minutes.

If vegetables are used in the culinary process in shredded form, then shredding should be done immediately before the heat treatment process or before serving raw.

When cooking vegetables, use a minimum amount of water.

Place vegetables in boiling salted water.

Add vegetables in small portions to ensure constant simmering.

Cook vegetables until the required stage of softening, but no longer than 20 minutes. with the lid closed, avoiding frequent stirring.

Serve vegetables immediately after cooking.

2.4. C-VITAMINIZATION OF NUTRITION.

Mandatory, year-round C-vitaminization nutrition is carried out in hospitals, sanatoriums, maternity hospitals, sanatoriums, homes for the disabled and the elderly, and dietary canteens. With the permission of the Center for Sanitary and Epidemiological Surveillance (CSES), which controls the C-vitaminization of prepared food in these institutions, the latter need not be carried out if fruit and vegetable dishes, rosehip drinks and other natural vitamin carriers constantly used in the diet contain amounts of vitamin C that correspond to physiological standards. may allow a temporary (seasonal/) break in C-vitaminization based on laboratory control data of the relevant dishes. C-vitaminization is carried out in the catering unit by a dietician. The first or third courses of lunch are fortified daily. It is preferable to fortify third courses, including tea. Fortification of ready-made dishes is carried out immediately before their distribution. Heating fortified foods is not permitted. Dose of administered ascorbic acid: 80 mg for adults, 100 mg for pregnant women, 120 mg for breastfeeding women. Method for fortifying first courses and compotes: ascorbic acid tablets, calculated by the number of servings (or weighed ascorbic acid in powder), are placed in a clean plate, where 100-200 ml of the liquid part of the dish to be fortified is poured in advance, and dissolved while stirring with a spoon, after which is poured into the total mass of the dish, stirring with a ladle. The plate is rinsed with the liquid part of this dish, which is also poured into the total mass. When fortifying jelly, ascorbic acid is introduced into the liquid in which potato flour is stirred. The person responsible for fortification daily enters information about the fortification being carried out into the menu layout or a special journal for fortification of ready-made dishes, indicating the name of the fortified dish, the number of fortified portions, and the amount of ascorbic acid introduced into the total mass of the dish. Ascorbic acid used for fortification is stored in a dry, cool place, protected from light, in a tightly closed container.

2.5. SOME SPECIAL METHODS FOR DIAGNOSTICS OF VITAMIN C DEFICIENCY.

The vitamin C LOAD TEST is based on the fact that there is no vitamin C depot in the body. When vitamin C is completely or partially removed from food, its excretion in the urine decreases or stops as tissue reserves are depleted. When massive doses (200-400 mg) of ascorbic acid are taken orally, the amount excreted in the urine increases sharply as the body becomes saturated with the vitamin. Method technique: determine the content of ascorbic acid in the daily amount of urine. Then 300 mg of ascorbic acid is prescribed daily (several days in a row). 4-7 hours after taking the vitamin, the content of ascorbic acid in urine samples is determined. Under normal conditions, a person excretes 20-50 mg of vitamin C every day in urine.

CAPILLARY TEST. A jar is placed on an area of ​​skin (usually the inner surface of the forearm), pre-lubricated with Vaseline, from under which air is pumped out and a negative pressure of 200 mm Hg is created. After 2 min. The jar is removed and, using a magnifying glass, the number of petechiae on the skin is counted, which in a healthy person should not exceed 5-6. If there are a large number of petechiae, a second sample is made, moving the jar to an adjacent area. And repeat the test at a pressure of 175 mmHg. If the number of petechiae is more than 5-6, then the test is repeated at a pressure of 150 mmHg, 125 mmHg, 75 mmHg. etc., until, as a result of the test, the number of petechiae is no more than 5-6. With C-hypovitaminosis, the pressure required for this ranges from 175-125 mmHg; with scurvy, it drops to 75 mmHg. and below. The capillary test is not specific for hypovitaminosis C, because An increase in the permeability of the vascular wall can occur after suffering many infections and other conditions of the body. Therefore, we can talk about hypovitaminosis C when using this test only when we examine large organized groups of people under the same living and nutritional conditions.

INTRASKIN TEST is based on the ability of ascorbic acid (as a strong oxidizing agent) to discolor Tillmans stain and convert it into leucoform. In the area of ​​the inner surface of the skin of the forearm, free from blood vessels, 0.05 ml of sterile Tillmans paint is injected intradermally. Make 2 injections and determine the average time of skin discoloration. If the bleaching time is less than 5 minutes, this indicates that the body is optimally supplied with vitamin C. The paint bleaching time is 5-10 minutes. corresponds to a satisfactory level of vitamin in the body. If the reagent discolors for more than 18 minutes, then there is a deficiency of vitamin C in the body.

But none of these methods alone can be decisive in the diagnosis of hypovitaminosis C. The final judgment can be made on the basis of laboratory data in combination with the results of clinical examinations.

In addition, it is advisable to use as a control when carrying out these tests. determination of vitamin C in blood serum. The physiological norm for vitamin C in blood serum is considered to be 0.7-1.2 mg%. If less than 0.5 mg% is detected, this indicates a lack of vitamin C in the body, i.e. about hypovitaminosis.

2.6. METHOD FOR DETERMINING A-HYPOVITAMINOSIS STATE.

With a lack of vitamin A in food or if its absorption is impaired, it is observed dark adaptation disorder. In severe cases, this is clinically manifested hemeralopia (night blindness)- more or less significant decrease in vision in twilight or night lighting conditions. To determine dark adaptation disorder, a study of the state of the Purkinje phenomenon is carried out.The essence of the latter is as follows: The sensitivity of our eye to light waves extends over a certain range of wavelengths, the limit of which is limited to the visible spectrum (red, yellow, green, blue, violet). During the day, the color yellow seems the brightest to us, and on either side of it the brightness decreases. At dusk this ratio changes. For a normal eye, under these conditions, the maximum brightness moves from yellow to the right and lies in the green part of the spectrum. The brightness of red color decreases so much that it is inferior to blue. This shift in color brightness from the red end to the blue, characteristic of a normally functioning eye at dusk, is called Purkinje phenomenon. When hemeralopia appears, adaptation is weakened or disappears altogether. Therefore, the Purkinje phenomenon occurs later or is completely absent. The principle of studying the state of the Purkinje phenomenon was used in the design of devices intended for studying dark adaptation, in particular Kravkov-Vishnevsky adaptomer, inside of which there is a table with four colored squares, selected so that the ratio of their lightness in the case of daylight or twilight lighting is different. This table is placed inside the device and is illuminated through a slit cut in one of the side walls. Before the test, the subject's eyes are adapted to a certain brightness. The state of color perception of the object under study is judged by the time it takes for it to perceive the ratio of lightness on a color table. The ADM adaptometer also allows you to judge the state of “night” vision and the degree of A-hypovitaminosis. A short-term (3 min) study is based on determining the time between the end of light adaptation and the moment when an object of a given brightness is noticed.

INDEPENDENT WORK OF STUDENTS

1. Master methods for determining the content of ascorbic acid in blood, urine, and determination of the resistance of skin capillaries to negative pressure using Nesterov’s device. To evaluate the results of the capillary resistance test, the following criteria are recommended (Table 9):

Table 9. Criteria for assessing a test for capillary resistance

2. Solving situational problems