What vitamins are preserved after heat treatment. Heat treatment destroys vitamins in vegetables: truth or myth

Changes in vitamins in fruits and vegetables

Carotenoids are stable and their amount practically remains unchanged during heat treatment. There are very few vitamins of group B in plant products, and during hydrothermal treatment they turn into a decoction and are destroyed slightly.
Vitamin PP is not destroyed by boiling, exposure to oxidizing agents and light. It is one of the most stable vitamins.
For an animal organism, three substances are equivalent in biological action: pyridoxine, pyridoxal and pyridoxamine. All three compounds with the biological activity of vitamin B6 are resistant to heat, unstable to the action of oxidizing agents, such as peroxides, as well as swat.
Pantothenic acid is resistant to atmospheric oxygen at room temperature, it is destroyed by autoclaving and heating in acidic to alkaline solutions.
Biotin is resistant to heat and dilute acids and alkalis. Prolonged aeration and H2O2 do not affect its activity.
Choline is a colorless, alkaline, syrupy substance that is resistant to heat.
The greatest degree of destruction is observed in vitamin B6: when cooking spinach, it decreases by 40%; white cabbage by 36%; carrots by 22%.
Vitamin B12, when heated in aqueous solutions, is most stable at pH 7, at pH 2 there is a slow loss of activity, and at pH 9 - rapid destruction. Autoclaving of this vitamin at 121°C in a neutral medium for 15 minutes does not change its activity. It is destroyed in solutions under the action of light.
Vitamin A and carotene are highly reactive due to the presence of a large number of double bonds. They are unstable to heat in the presence of oxygen, but stable in its absence. Vitamin A in the absence of oxygen can be heated to 120-130 ° C without changing the chemical structure and loss of biological activity, it is destroyed by ultraviolet rays.
Vitamin D is resistant to high temperatures, as well as to oxygen, but when heated no higher than 100 ° C.
Tocopherols are resistant to heating up to 200°C in the presence of oxygen; destroyed by ultraviolet rays and some oxidizing agents.
Vitamin K is resistant to high temperatures, except for heating in an alkaline environment. Destroyed by ultraviolet rays.
Vitamin C undergoes significant changes. Ascorbic acid is oxidized by atmospheric oxygen under the action of an enzyme, it passes into dehydroascorbic acid. Upon further heating, both forms are destroyed. The rate of destruction of ascorbic acid depends on the properties of the processed semi-finished product, heating rate, duration of treatment, contact with atmospheric oxygen, composition and pH of the medium. The higher the content of vitamin C and less dehydroascorbic acid, the less it is destroyed. The faster the heating, the better the preservation of vitamin C, the faster the enzyme that oxidizes vitamin C is inactivated. The presence of oxygen, copper, iron, manganese in the cooking medium reduces the amount of vitamin C.
Vitamin C is less destroyed in an acidic environment. When vegetables are cooked in an acidic environment (tomato paste), vitamin C is better preserved (due to the weakening of the action of copper ions).
Ions of copper, iron, magnesium, contained in tap water or entering the cooking medium from the walls of dishes, catalyze the destruction of vitamin C.
Substances contained in vegetables and fruits (amino acids, vitamin A, E, thiamine, anthocyanins, carotenoids) prevent the destruction of vitamin C. Cooking in broth preserves vitamin C.
Storing food in a hot state, vitamin C is destroyed at room temperature. The greatest loss of vitamin C is during poaching. During frying, it is destroyed less than during hydrothermal treatment, since there is less oxygen access, rapid heating, and a short period of thermal exposure. In the manufacture of products from vegetable cutlet mass, up to 90% of vitamin C is destroyed.
Cutting vegetables and fruits leads to an increase in the destruction of vitamin C.

Unfortunately, during cooking, a significant part of the vitamins and trace elements are destroyed. For example, while you cook soup, cabbage loses almost half of the folic acid, beans and peas lose about 40% of their calcium, and carrots and spinach lose a third of vitamin E. Vitamin C is destroyed by 70% during cooking.

However, these losses can be reduced. It is only necessary to follow a number of simple recommendations.

Vegetables must be completely covered with water. If the broth has boiled away too much, do not add cold water to the pot. Together with it, oxygen enters the broth, which destroys vitamin C. For the same reason, try to keep the lid of the pan tightly closed.

If you are adding a mixture of frozen vegetables to your soup, do not defrost the vegetables before tossing them into the pot.

The less time vegetables spend in water, the healthier they will be. And if so, try to put them in boiling water, and not in cold water. Be careful not to overcook the vegetables.

Do not put all the products in the pan at the same time. The meat takes about an hour to fully cook. If you put it together with potato slices, which will reach readiness in 20-30 minutes, the latter will lose almost all the vitamins they contain.

And remember that, despite the loss of vitamins, there are still benefits from boiled vegetables and compotes. They contain quite a lot of fiber and pectins. These substances reduce the level of bad cholesterol in the blood and improve digestion.

In a double boiler

This method of cooking is considered one of the healthiest.

During steam cooking, food is not exposed to too high a temperature - the cooking process takes place at a temperature of about 100 degrees, while, for example, baking in the oven takes place at 250-300 degrees. Such a low temperature allows the products to retain a maximum of useful substances. Not so long ago, researchers conducted an interesting experiment. They took broccoli, split it in two, boiled half in a pot and put the other half in a double boiler. Then the scientists measured the amount of nutrients in the finished cabbage. Boiled broccoli has lost approximately 40% of its vitamins, while steamed broccoli has lost only 11%.

Another advantage of a double boiler is that it allows you to cook the most juicy vegetables, meat or fish. The surface of the products in contact with steam is "sealed" and the juice does not flow out.

Well, and of course, there are a lot of fans of steam cuisine among those who want to get rid of extra pounds, because steamed dishes contain much less fat than fried or baked ones.

in a frying pan

Compared to boiling, frying preserves much more vitamins. For example, in a frying pan, the loss of B vitamins is approximately 30%, while in a pot of water, 70% of these substances disappear.

The healthiest method of frying is fast frying, when finely chopped foods are spent in a pan for no more than five minutes, and deep-frying is considered the most harmful. Floating in a huge amount of oil, french fries become very fatty and high in calories. However, it is worth remembering that the loss of vitamins is not the worst thing that happens to your food during the frying process. Much more dangerous are carcinogens that are formed during frying over an open fire, when vegetable oil is heated for too long, and if the oil is reheated. It is believed that these substances can cause malignant tumors. Therefore, if you cannot live without fried, use only fresh oil each time, do not heat it to such a temperature that it begins to smoke. Remember that carcinogens are "afraid" of acidic marinades. Therefore, if you want to cook meat on the grill, then carefully soak it in vinegar, juice or wine. And of course, do not forget the spices. Kansas biochemists have found that the use of seasonings, which are natural antioxidants, can reduce the level of carcinogens in fried foods. Adding a small amount of ground dried ginger or cumin to chopped ground beef leads to the fact that 40% less carcinogens are released. Rosemary extract, a herb that invariably accompanies roast lamb in classical European cuisine, reduces the amount of harmful substances by almost 70%. Spices characteristic of the culinary traditions of Southeast Asia (coriander, ginger, lemongrass, cumin, sesame and others) "kill" 30-35% of carcinogens in fried meat.

In the bank

In the summer, you spent a lot of energy preparing homemade pickles and marinades. These simple canning methods allow you to save almost all the vitamins and minerals that are found in fresh vegetables. At the same time, some canned vegetables turn out to be even more useful than the “source raw materials”. A classic example is sauerkraut. Lactic acid bacteria, which are released during fermentation, allow you to completely preserve all the vitamins, while in fresh cabbage some of the vitamins are destroyed during storage.

Soaked apples are also sometimes healthier than their fresh counterparts. If fresh apples lie down for at least a couple of weeks, they lose approximately one third of the vitamin C they contain, while ascorbic acid is completely preserved in soaked apples.

However, it is better for heart patients and hypertensive patients not to abuse pickles and marinades. The fact is that these canned foods contain too much salt, and this can lead to an increase in blood pressure. Spicy snacks such as lecho, pickled tomatoes and peppers are contraindicated for people suffering from gastritis and peptic ulcer.

in the freezer

Freezing is one of the best ways to preserve vitamins. But if you don’t want to subsequently “lose” useful substances, do not wash frozen fruits and vegetables and do not defrost them in water - this will “wash out” a significant part of the vitamins. By the way, according to a new study by Austrian scientists, frozen vegetables are often healthier than imported "fresh" ones, which are sold in supermarkets out of season.

Researchers say fresh-looking vegetables that travel a long way before hitting the shelves lose a lot of their vitamins and minerals. Frozen vegetables, on the other hand, are often processed only a few hours after being harvested, and their nutritional value is preserved. Scientists compared the nutritional value of frozen foods and imported fresh vegetables sold in the winter. The content of vitamins in frozen peas, cauliflower, beans, corn and carrots turned out to be much higher than in imported fresh vegetables from Italy, Spain, Turkey and Israel.

Mikhail Turetsky:

“I can’t call myself a gourmet or say that I eat exclusively gourmet food. Since I am away from home for seven months of the year, most of all I miss homemade borscht and cutlets.

It is known that the inventor of canned food, French chef Nicolas Francois Appert, was awarded the title of "savior of mankind." And the saved humanity, turning the banks every year, asks a more urgent question: are their labors in vain? Are vitamins preserved in canned food?

Salting, pickling, urinating

“Salting and fermentation practically do not destroy the vitamins and biologically active substances contained in the original products,” says Boris Sukhanov, professor at the Institute of Nutrition of the Russian Academy of Medical Sciences and the Sechenov Moscow Medical Academy. “Vitamin C, for example, is higher in sauerkraut than in fresh cabbage.”

Pros. The most simple types of canning. Fermented juice stimulates digestion and has an immunostimulating effect. Soaked foods replenish the reserves of trace elements in the body.

Minuses. Salty addiction can trigger an outbreak of hypertension. People who suffer from a tendency to edema should also refuse pickles. Excess lactic acid can damage the lining of the stomach.

Special marks. It is necessary to store pickles, urination and fermentation at a temperature of + 6-8 ° C.

Pickling

Preservation of useful properties."Marinating completely preserves vitamins such as beta-carotene, thiamine and riboflavin, says Professor Boris Sukhanov. Marinades are champions in vitamin C content."

Pros. Pickled foods are appetizing.

Minuses. Marinades due to high acidity and vinegar content are contraindicated for people with a disease of the gastrointestinal tract.

Special marks. The main danger that hides under the lid of cans is botulism. So that your blanks do not become a source of infection, do not clog the jars "to the eyeballs". Free space will ensure the presence of oxygen in the jar and block the path of the disease.

Drying

Preservation of useful properties. Vitamins remain much less than with other types of preservation. The concentration of proteins, fats, carbohydrates in comparison with fresh fruits increases by 9-10 times.

Pros. Dried prunes perfectly stimulate intestinal motility and help to cope with constipation; dried blueberries eliminate intestinal upset; Dried raspberries are an excellent diaphoretic. There is a lot of ascorbic acid in dried rose hips, and potassium in dried apricots and peaches.

Minuses. Dried fruits are 5-7 times more nutritious than fresh ones, so if you have a tendency to be overweight, dried fruits should not be abused.

Special marks. Greens, if it is properly dried, retain up to 30% of vitamins, which is a lot, because dill, for example, has no less vitamin C than lemon.

Freezing

Preservation of useful properties. Quick freezing is one of the most gentle ways to preserve vitamins in foods.

Pros. Frozen vegetables and fruits do not contain preservatives, retain their taste, and have a low calorie content.

Minuses."If stored incorrectly, frozen vegetables and fruits lose their useful properties," warns Galina Kholmogorova, a leading researcher at the State Research Center for Preventive Medicine.

Special marks. Frozen foods cannot be washed - water washes out vitamins and spoils the taste. It is necessary to cook them without prior defrosting, immediately throwing them into boiling water or into a hot frying pan. The longer you store, the less vitamins become.

Cooking

Preservation of useful properties. Jams, jams, jams retain only 10-30% of vitamins.

Pros. In jams, as in all other canned vegetables and fruits, fiber, pectins remain - substances that slow down and suppress the processes of decay and gas formation, and help reduce blood cholesterol levels.

Minuses. When preparing jams, the content of vitamin C in plums decreases by 3 times, in currants - by 5 times, in apples - by 6-7 (!) times. Jam or jam contains 2-3 times less carotenoids and B vitamins, 4-5 times less nicotinic acid than in the original products.

Yes, cooking methods change the composition of nutrients in vegetables and fruits, but this is not always a bad thing.

Cooked vegetables and fruits may contain more of some nutrients than fresh ones.

Several scientific studies have shown that cooking can reduce some nutrients while increasing the availability of others. In the end, there is no single “correct” or best cooking method, including eating vegetables and fruits raw.

Many people believe that raw vegetables and fruits have more vitamins than cooked ones, but this depends on the type of nutrients.

In one study in Germany of 200 people, if raw vegetables and fruits were eaten, as a result of this diet, the subjects had higher than average levels of beta-carotene (a precursor of vitamin A), but plasma levels of lycopene (another “version”, an isomer of beta-carotene) were well below average. And this is not surprising, since fresh tomatoes have lower levels of lycopene than cooked ones. Roughly speaking, in the process of cooking fruits, the cell walls of plants “break” and the nutrients stored in them are released.

Cooking reduces vitamin C and B vitamins

Water soluble vitamins such as C and B vitamins are more susceptible to degradation during cooking. For example, canned peas lose 85% to 95% of their natural vitamin C levels. Cooking spinach lowers its vitamin C content by 2/3.

Depending on the way vegetables and fruits are cooked, they lose 15-55% of their vitamin C, according to a study by scientists at the University of California.

It has also been observed that the level of vitamin C in freshly frozen foods is even higher than in fresh ones, because its content decreases rapidly during storage and transportation of fresh vegetables and fruits.

Boiled carrots have more carotenoids than fresh ones.

Fat-soluble vitamins A, D, E, K and carotenoids feel much better during cooking. A report from the Journal of Agriculture and Food Chemistry concluded that boiling carrots, broccoli, and zucchini better for preserving these vitamins than frying and baking, and even better than serving them raw.

Boiling carrots will INCREASE their carotenoids(vitamin A precursors) compared to raw carrots, but will reduce the level of polyphenols, which are destroyed during cooking.

As for cooking not only vegetables and fruits, it is important to recall that frying foods provokes the appearance of AGEs (glycation end products) in food - harmful carcinogens. For example, fried eggs contain about 15 times more AGEs than boiled eggs.

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Microwave cooking preserves vitamins

Many people think that cooking in the microwave "kills" vegetables and fruits. Actually Microwaving even boosts some vitamins.

Microwaved broccoli retains more vitamins than fried or boiled broccoli.

In March 2007, a study was conducted on the effects of boiling, roasting, microwaving, and pressure cooking on the vitamin content of broccoli.

• During baking and boiling, 22-34% of vitamin C was lost.
• When cooking in the microwave and slow cooking under pressure, about 90% of vitamin C was retained.

conclusions

There is no perfect way to cook and preserve all the nutrients in fruits and vegetables (except if possible, avoid frying in favor of other methods).

Diversity in food, which Zozhnik actively promotes as the best health preventive measure, also applies to a variety of cooking methods - remember that boiled carrots have more carotenoids, but less polyphenols, and vice versa in fresh ones.

In the season when the ripening of fruit crops stops, the human body still needs vitamins. Therefore, you have to look for methods to stock up on sources of useful substances in advance. Many have long come to the decision that it is very convenient to freeze fruits in the summer, thus preserving them for the winter. But the question is, are vitamins stored in frozen berries?

Before you figure out whether the fruits remain the same useful after freezing, you need to find out what fresh berries are initially rich in.

Vitamins in fresh fruits

The most popular berries that gardeners and gardeners plant in their plots are strawberries, cherries, raspberries, gooseberries, and currants. And if you remember the forest fruits, then lingonberries, blackberries, blueberries, cranberries will be added.

The vitamins found in all these fresh crops are shown in the table:

Berries are indispensable for the human body. If you regularly eat them, you will be able to improve your health, improve the functioning of internal organs and strengthen your immune system. In addition to the vitamins listed in the table, berries contain other useful substances: chlorine, magnesium, calcium, potassium, iron, copper, zinc, phosphorus, sulfur, sodium and others.

There is no doubt that they are useful in their original form, but are useful substances and vitamins preserved in berries that are frozen and have lain for a long time?

Are useful qualities preserved after freezing?

Vitamins in berries are preserved after freezing, if you follow the recommendations for freezing. Putting them in a freezer at a temperature of -18 ° C in a sealed package, you can be sure that most of the nutrients will be stored for up to 8 months.

In winter, the price of store-bought berries is very high, and the benefits of such a purchase are doubtful. The vitamin composition after cold treatment remains almost the same as in a fresh product, but at the same time there is an exact certainty that the fruits will not harm the body.

Before proceeding with the preparation of freezing, you need to determine the required number of berries. It is best to roughly calculate how much is eaten in the summer, and freeze the same amount for the winter.

If the fruits are already harvested, the freezing process should be started as soon as possible. Every day the vitamin composition of the product decreases, and it loses its value. You can store the harvest indoors before freezing for no more than two days.

Spoiled and damaged berries are not suitable for freezing, therefore, initially you need to sort out the entire crop. Along with this, you need to remove all sticks, leaves and debris, if any. If you skip this point, the fermentation process may begin.

All berries must be washed, carefully so as not to violate the integrity, and then dried on paper or a towel.

Soft fruits need to be frozen in two stages:

• After washing, you need to dry them on a tray. on which they will be placed in the freezer for the initial freezing, so they will not be damaged.
• And after - get and quickly transfer to containers or bags , for compact storage.

After everything is placed in the freezer, you need to set the temperature as low as possible, ice, when slowly freezing, breaks the structure of the berries.

It is impossible to defrost and freeze stocks several times, so they will lose their useful qualities and lose their shape. You need to prepare in advance and divide everything into portions, after which in the winter it remains only to defrost and cook a dish from them.

If you prepare stocks incorrectly, storing them for the winter will be useless. If you skip any of the steps at the preparation stage, they can not only lose vitamins, but even be harmful.

How to Consume Frozen Stocks

You need to defrost them in the refrigerator, so you can keep their shape and attractive appearance. It is best to get the right amount an hour or a half before use. Once completely frozen, delicious supplies are ready to eat.

Do not defrost the fruits in the microwave, after such processing they will lose a significant amount of nutrients, and the taste will be different from fresh ones.

Thawed berries can be consumed as an independent product or added to dishes. Breakfasts with such additives will be very nutritious. Also, such blanks can be used for making juices, compotes and for baking.

Benefits and contraindications for use

Berries are a natural antioxidant, it is necessary to eat them, especially during a period when the body is prone to infections, colds and viruses. If you understand the composition and find out which of them have the most useful substances, it will be clear which ones are worth stocking up.

Blackcurrant, for example, contains more vitamin C than. In 100 grams of blackcurrant, there are 200 mg of vitamin, and in a lemon, 40 mg are for the same weight. Moreover, blackcurrant is tasty and can be easily eaten in large quantities, but not everyone will just chew lemon.

Including various berries in your diet can help improve skin condition, normalize blood cholesterol levels, reduce the risk of memory problems and age-related diseases, and prevent joint diseases. They will help to improve the condition during the period of illness, the main thing is to decide what result is needed and choose the collection that is necessary in a particular case.

Berry mixes are very effective for those who want to lose weight, they satisfy the feeling of hunger and at the same time help burn fat.

People who experience digestive problems, suffer from stomach ulcers or gastritis, should be careful when eating berries, it is best to consult a doctor. With diarrhea and indigestion, it is completely worth abandoning this product, the problem may worsen.

Remember that moderation is necessary in everything: despite the fact that berries are useful, their overabundance can worsen the condition of the teeth and discolor the skin.

Freezing fresh vitamins is very profitable and convenient, if you stock up on healthy products in advance, in winter you will always have natural medicines and goodies for the whole family at hand.