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High temperature, toxic metamorphic food?

01/06/2019 | Food safety
Most of the food purchased often requires a certain amount of processing or cooking to be eaten. During hot processing ...

Most of the food purchased often requires a certain amount of processing and cooking to be eaten. During hot processing, nutrients are subjected to a variety of physicochemical changes. So, how does high temperature interact on food? How should food be processed so that nutrients are not depleted and the production of toxic substances is prevented? This article will help readers understand.

With protein (protit):
When heated at 700C, the protit clumps and then degrades. In the presence of acid, this process occurs at lower temperatures. Moderately compacting makes the protit digestible. When cooking at high temperatures for too long, the nutritional value of the protit decreases because of indigestible bonds. This process often happens when grilling, steaming food in high temperature ovens, frying food in grease for too long (when fried food in grease can reach temperatures above 2000C, when baking food on charcoal , temperature can be up to 3000C). Therefore, for protein-supplying foods such as meat, fish and eggs, all must use temperatures above 700C and should be 1000C to cook and kill bacteria (including bacteria and viruses). When boiling chicken (goose, duck), fish, spring rolls, liver ..., need to be boiled carefully, paying special attention to the flesh close to the bones so that no longer pink. Limit the use of grilled, roasted and fried foods in high temperature furnaces or in greases for a long time.

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With fat (lipit):

At temperatures not exceeding 1020C, lipid (oil, grease) has no significant changes other than liquefaction. When heated for a long time at high temperatures, the unsaturated fatty acids will be oxidized and will be useless, and the double bonds in the structure of these acids will be broken down to form intermediate products such as peroxides. Aldehydes are harmful to the body. When grilling food on the fire, the fat flows down to create a fragrance, but it is actually aromatic aromatic carbuahydro which is not good for the body and that is one of the carcinogens. Therefore, you should not reuse fried oil at high temperatures many times, do not buy fried foods, commercially available roasters (donuts, donuts, roasted chicken ...).

With flour (gluxit):

Including simple sugars, double sugars, starches, cellulose. At the boiling temperature, simple sugars have no significant changes. Hot processing makes the starch more digestible, the cellulose does not crack and becomes softer, allowing digestive juices to come into contact with the nutritional components in plant cells (usually the cellulose forms a membrane). wraps around the cells of nuts, tubers, vegetables ...). But when processed at high temperatures, especially in a dry environment without water, the components of starches are also altered indigestible or toxic to the body.

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After boiling and cooking vegetables, you should eat immediately to limit the loss of vitamin C.

The minerals (calcium, phosootspho, potassium, magnesium ...) in the cooking process have the number of changes because they dissolve into the water. Therefore, it is advisable to use both the female and the water.


Vitamins suffer the most changes because they are relatively less stable.

Fat-soluble vitamins such as A, D, E, K are relatively stable with temperature, during normal cooking, this group of vitamins is lost by 15-20%. Water-soluble vitamins are lost more because they are dissolved and easily broken down, especially in an alkaline environment. Therefore, soaking food in water, boiling a lot of water and then pouring it, using caustic soda (or lime) in cooking, preserving food for long will cause a lot of B, C vitamins (the amount of loss can be up to 90 %).

Of the B vitamins, vitamin B1 is the least stable, vitamin B2 and vitamin PP are almost not degraded. When boiled meat, fish, a relative amount of B vitamins out of the broth. Properly heated processing loses about 20% of the B vitamins, particularly the loss of vitamin B1 may be higher.

Vitamin C is least sustainable. Not only is it readily soluble in water, it also oxidizes rapidly, especially at high temperatures. During storage, the amount of vitamin C also decreases. Therefore, should choose fresh fruits and vegetables to wash food before peeling, slicing, cutting; Once cut, cut and cook immediately. The oxylase released when the vegetable is hit is also involved in the oxidation process, which causes the vegetable to spoil quickly and the amount of vitamin C to disappear very quickly. When boiling, cook vegetables into boiling water when vegetables have been washed (to eliminate the effect of oxylaza) to shorten the cooking time. After cooking, it also helps to reduce vitamin C loss.

It is estimated that the amount of vitamins lost due to cooking is as follows: vitamin C: 50%; vitamin B1: 30%; carotene: 20%.

In short, it is necessary to process foods at the appropriate temperature to ensure that nutrients are not deformed, wasted, and ensure food hygiene and safety to help the body absorb and make good use of nutritional ingredients. and prevent the production of toxic substances.

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