How much vitamins do you lose by heating vegetables, and how much vitamins do you lose when vegetabl

Vitamins will be lost anyway.

Heating has different effects on different vitamins, and the temperature and time at which various foods are "heated" are also different, so it is not easy to answer the question of "how much vitamin is lost when cooked". The USDA database contains the various vitamin levels of common foods. Someone has counted the data on various foods in their "raw" and "cooked" states, and while these figures are not necessarily very accurate, they are enough to draw a meaningful conclusion:

Vitamins A and E are not affected by temperature, losing about 10% after cooking, vitamin C about 16%, and vitamin B1 is the most unstable, losing 26%, and other vitamins are basically within this range. Overall, the loss of vitamins when food is cooked is roughly between 10% and 25%.

But heating also has a positive effect on vitamins. Some foods contain so-called "antivitamins", which bind to vitamins and are destroyed by heating, increasing the absorption rate of vitamins. Carotene is another example that is found in a variety of vegetables such as carrots, spinach, sweet potatoes, broccoli, etc.

When it reaches the human body, it can be converted into vitamin A, which is the main way for vegetarians to obtain this vitamin. However, the absorption rate of carotene in raw vegetables is very low, and heating can greatly increase its absorption rate.

10% to 25% of the heating loss, which is not a lot and not too little. However, given the problems that can arise from eating vegetables raw, such as disease-causing bacteria, and some toxins that need to be destroyed by heat, it is difficult to simply say whether vegetables should be eaten raw or cooked. In fact, for vitamins, instead of focusing too much on "loss", it is better to focus on **.

Different foods are rich in different vitamins, and if the food you eat is more diverse, then the total amount of various vitamins is naturally more, and it doesn't matter if you lose a little. After all, what our body needs is a certain amount of every type of vitamin, not a certain amount of one or two, the better.

Due to people's negligence or the wrong method used in cooking, a large amount of vitamins in vegetables are unknowingly destroyed or lost. It's a pity. Vitamin loss can be avoided as much as possible as long as the following are done: Vegetables are stored soon.

Fresh vegetables, bought and stored at home do not eat, will slowly lose some vitamins, such as spinach at 20 years, vitamin C loss of up to 84%, if you want to preserve vegetables should be stored in a dark, ventilated and dry place.

The most vitamin-rich part is discarded.

For example, some people eat only the sprouts on the top and throw away the beans, in fact, the beans contain 2-3 times more vitamin C than the sprouts, so it is a pity to lose them. Again, to make dumpling filling, squeeze out the vegetable juice, vitamins will lose more than 70%, the correct way is to cut the vegetables with oil first, and then add salt and seasonings, so that the salt can not enter, the filling will not come out of the soup.

Rinse properly. Some people cut the vegetables and wash them. This can easily lead to a large loss of vitamins.

Don't stir-fry in a copper pan.

Because copper promotes the breakdown of vitamins C and B1.

Do not add a lid when cooking.

Some people like to cover the lid of the pot when cooking vegetables, which is unscientific. If you cover the pot and cook the vegetables, the vitamin B2 in the vegetables will be lost by 15-20%.

Do not cook for too long when cooking.

Vitamin C, B1 of green vegetables are afraid of heat, afraid of cooking, according to the measurement, the loss of vitamin C is only 17%, if fried and then simmered, the loss of vitamin C in the dish is 59%, therefore, the cooking should be done with a strong fire, so that the dish is not only delicious, but also the nutrient loss in the dish is less, add a little vinegar when cooking, it is also conducive to the preservation of vitamins. There are also some vegetables, such as cucumbers, tomatoes, etc., which are best eaten raw.

Cooked dishes should be eaten immediately.

In fact, the vitamin B1 in vegetables can lose 25% in the process of warming after burning, and if the cabbage is warm for 15 minutes, it can lose 25% of vitamin C, 10% if it is kept warm for 30 minutes, and 20% will be lost if it is extended to 1 hour. If the vitamin C in the vegetables is lost by 20% in cooking, 25% in the soup, and if it is warmed on the fire for another 15 minutes, it will lose another 20%, a total of 65%, then we will not get much vitamin from the vegetables.

Eat vegetables and drink soup.

Many people love to eat vegetables but do not like to drink vegetable soup, in fact, when cooking vegetables, most of the vitamins will be dissolved in the vegetable soup, take vitamin C as an example, after the cabbage is fried, 70% of the vitamin C will be dissolved in the soup, fresh peas are boiled in water for 3 minutes, and 50% of the vitamin C is dissolved in the soup.

Negligence or the use of traditional wrong methods in cooking can cause a large amount of vitamins in vegetables to be destroyed or lost unconsciously. Common mistakes are:

1) Long-term vegetables: fresh vegetables, bought and stored at home without eating, can lose some vitamins. For example, spinach at 20 years old loses 84 vitamin C. If vegetables are to be preserved, they should be stored in a dark, ventilated and dry place.

2) Discard the most vitamin-rich part. For example, bean sprouts, some people only eat the sprouts on top and throw away the beans. But I don't know that the vitamin C contained in the beans is 2 3 times more than the part of the sprouts, and then, to make dumpling filling, squeeze out the vegetable juice, the vitamin will lose more than 79.

The correct way is to cut the vegetables, mix them with oil first, and then add salt and seasonings, so that the oil cabbage can't get in salt, and the filling won't come out of the soup.

3) Chop the vegetables before rinsing. When washing and cutting vegetables, some people often cut them first and then wash them. However, I don't know that most of the vitamins in green vegetables can be dissolved in water, and if the vegetables are cut and rinsed, a large amount of vitamins will be lost to the water.

4) Cook the dishes in a copper pot. Because of its ability to promote the breakdown of vitamins C and B1, copper pots are known as the "enemies" of vitamins.

5) Cook without a lid. This is also often overlooked, if the lid is covered to cook vegetables, the vitamin B2 in vegetables only loses 15 20, if you don't cover the lid, it can be 2-3 times more. Cooking for 7 minutes without a lid loses the same amount of vitamin C as it does when cooking for 25 minutes with the lid on, and vitamin A is also easily destroyed.

6) Cook the dish for too long. The vitamins C and B1 in green vegetables are afraid of heat and cooking. According to the measurement, the loss of vitamin C in the dish is only 17, and if it is simmered after stir-frying, the loss of vitamin C in the dish is 59.

Therefore, the cooking should be done with a strong fire, so that the dishes are not only delicious in color, but also have less nutrient loss in the dishes. Adding a little vinegar when cooking vegetables is also conducive to the preservation of vitamins. There are also some vegetables, such as cucumbers, tomatoes, etc., which are best eaten raw.

7) Don't eat the cooked food right away. In order to save time, some people like to cook the dish and then warm it in a pot and wait for the next meal to be hot. In fact, vitamin B in vegetables can be lost in the process of warming after burning25.

Vitamin C25 can be lost if the cabbage is warmed for 15 minutes, 10 if it is kept warm for 30 minutes, and 20 if it is extended for 1 hour. If the vitamin C in the greens loses 20 in cooking, 25 in the soup, and if it is warmed over the fire for another 15 minutes, it loses another 20, for a total of 65, then there is not much vitamin left from the greens.

8) Eat vegetables and don't drink soup. Many people love to eat vegetables but do not like to drink vegetable soup, but they do not know that most of the vitamins will dissolve into the vegetable soup when cooking vegetables. Take vitamin C as an example, after the cabbage is fried, 70% of the vitamin C will be dissolved in the soup, fresh peas will be boiled in water for 3 minutes, and 50% of the vitamin C will be dissolved in the soup.

1. In the cooking process, from the washing of raw materials, primary processing to cooking, various vitamins in food will be lost to varying degrees due to water immersion, heat, oxidation and other reasons, resulting in a decrease in the nutritional value of the meal.

The loss of vitamins during cooking is mainly due to the nature of vitamins. The relevant nature of the loss is mainly caused by the following aspects.

1 Oxidation reaction.

Oxygen-sensitive vitamins include vitamins A, E, K, B1, B12, C, etc., which are easily destroyed by oxidation during the cooking process of food. In particular, vitamin C is very unstable to oxygen, especially in aqueous solution, it is more susceptible to oxidation, and the rate of oxidation is closely related to temperature. The longer the cooking time, the more vitamin C is oxidatively lost, so the heating time should be shortened as much as possible during cooking to reduce the loss of vitamin C.

2 Solubility.

Water-soluble vitamins in the cooking process because of the more water added or the more soup overflow, and the more vitamins dissolved in the soup of the dish, the degree of soup overflow is related to the cooking method, generally using steaming, boiling, stewing, burning and other cooking methods, the soup overflow amount can reach 50, so the content of water-soluble vitamins in the soup is larger; Stir-frying, slipping, boiling and other cooking methods are used, and the cooking time is short, especially the raw materials are thickened and the soup does not overflow much, so the amount of water-soluble vitamins precipitated from the raw materials of the dish is not much.

Fat-soluble vitamins such as vitamins A, D, K, E, etc. can only be dissolved in fat, so the raw materials of dishes will not be lost when rinsing with water and cooking with water as a heat transfer medium, but when oil is used as a heat transfer medium, some fat-soluble vitamins will be dissolved in oil. Adding edible oil to coleslaw can not only increase its flavor, but also increase the body's absorption of fat-soluble vitamins in coleslaw.

3 Thermal decomposition.

In general, water-soluble vitamins have poor stability to heat, while fat-soluble vitamins are more stable to heat, but the exception of easy oxidation, such as vitamin A is more stable to heat when isolated from air, but the degree of damage caused by long-term heating in the air will increase with time, especially fried food, because of the high oil temperature, it will accelerate the oxidative decomposition of vitamin A.

4 The role of enzymes.

In animal and plant raw materials, there are a variety of enzymes, some enzymes also have a decomposition effect on vitamins, such as the anti-biotinylase in egg white can decompose biotin, and the ascorbate oxidase in fruits and vegetables can accelerate the oxidation of vitamin C. These enzymes are inactive after 10 to 15 minutes of heat treatment at 90 100. For example, the oxidation rate of vitamin C in unheated vegetable juice is faster due to the action of oxidase, and after heating, the vegetable juice is inactivated by oxidase, and the oxidation rate of vitamin C is slowed down accordingly.

How to cook to minimize vitamin C loss in vegetables? With such doubts, the journalist conducted an experiment. It was found that vegetables heated in the microwave oven had a higher proportion of vitamin C than raw vegetables.

According to the analysis, the reason for this situation is that the moisture in the vegetables turns into steam during the heating process, which leads to an increase in the proportion of dry matter in the vegetables, and if the lost water is taken into account, the content of vitamin C is slightly reduced by microwave heating.

The reporter then investigated the effect of boiling on vitamin C, he cut the vegetables into blocks, slices and shreds, and after boiling them for 10 minutes, he found that the more chopped the vegetables, the more vitamin C was lost.

However, if the same shredded vegetables are steamed, microwaved and fried in oil, it is found that whether they are steamed for 3 minutes, microwaved for 1 minute, or fried in oil for 3 minutes, vitamin C is not greatly reduced.

What do the results of these experiments show? "Vitamin C is a water-soluble vitamin, which is highly soluble in water, and the longer vegetables are soaked in water, the more vitamin C is lost," the expert explains.

The finer the chopped vegetables, the more cross-sections they will come into contact with the water, and the greater the amount of loss. But when fried in oil, the oil instead stops the loss of vitamin C. ”

In response to the statement that "the longer vegetables are heated, the more vitamin C is destroyed", experts believe that "it is not so much that it is destroyed, but that vitamin C is oxidized". However, even if it is oxidized, vitamin C can still play its original role in the human body, but if vitamin C is dissolved into the juice, it will inevitably lead to a decrease in the body's intake of vitamin C. Therefore, in cooking is rich in vitamin C

When vegetables, the contact between vegetables and water should be reduced as much as possible.

Blanching vegetables with a little salt or sugar can inhibit the loss of vitamin C.

So, what can you do to reduce the loss of vitamin C when you need to blanch vegetables? "First of all, we should reduce the amount of time vegetables spend soaking in water as much as possible. For example, if we want to blanch a whole bag of spinach, if we put the bag into the pot in one go, we must cook it for a longer time to achieve the blanching effect, so that vitamin C will be lost more.

Therefore, the correct way to do this is to blanch in water in small quantities several times, and the shorter the blanching time each time, the less vitamin C is lost. ”

In addition to reducing the boiling time, Yoshida also has a trick for everyone: add a little salt and sugar to the water. This is because when a little salt or sugar is added to the water, the density of the water in which the vegetables are cooked changes, and vitamin C is difficult to flow out under the action of osmotic pressure.

If you add a little salt, the color of the vegetables can still maintain a fresh and fresh state after blanching, and at the same time ensure the retention of nutrients in the vegetables, and if you add a little white sugar, the vegetables will taste faintly sweet and taste better. However, it should be noted that although the more salt and sugar are added, the better the vitamin C is retained, the taste and the intake of salt and energy should be considered comprehensively in the process of cooking.