1. Prevention of pesticide residues

　　Pesticide residues refer to pesticides and their metabolites, degradants or derivatives that remain on the surface and inside of food after pesticide application. Eating foods containing residual pesticides, large doses may cause acute poisoning or chronic poisoning; chronic intoxication may occur at low doses and long-term intake, as well as carcinogenic, fetal malformation and gene mutation. Vegetables and fruits are one of the most serious food hazards caused by pesticide residues. Although the relevant departments have formulated regulations on the rational use of pesticides for growing vegetables, the problem of pesticide abuse by vegetables and fruits is still prominent and widespread.

　　 In order to remove the residual pesticides in vegetables and fruits, the more reliable methods we recommend are: ① peeled or shelled; ② rinse under running water or simply clean and soak for about 20 minutes; ③ use special fruits and vegetables Detergent cleaning; ④ blanching or blanching. Other methods include washing with alkaline or hot water, ozone decomposition, etc., but these practices usually result in a large loss of vitamins and antioxidant components in fruits and vegetables, which is not worth the loss. Pesticide residues in vegetables can be reduced by 15% to 70% after cooking.

　　 2. Reduce the loss of nutrients

　　Vitamins and minerals contained in vegetables are mostly water-soluble, and some are unstable due to heat, it is easy to be lost or destroyed during cooking. In order to minimize the loss of nutrients, you can take the following measures:

　　 ① Wash first and then cut? Vegetables should be washed before changing the knife. If you cut first and then wash, a lot of water-soluble vitamins and minerals will be lost from the "wound". The picture is convenient, cut first and then wash, it will lead to low nutritional quality of vegetable dishes.

　　②Quick stir fry? The higher the temperature, the longer the heating time, the greater the damage to vitamins. Stir frying fast (high temperature, but short heating time) is more conducive to keeping vitamins from being destroyed than slow fire (low temperature, but long heating time). Quick-fire frying can also reduce water leakage, thereby reducing the loss of water-soluble nutrients. Experiments have shown that when vegetables are cooked for 3 minutes, vitamin C loses 5%, and if cooked for 10 minutes, vitamin C loses 30%.

　　 ③ Make fresh and eat now, eat less leftovers? The longer the fried vegetables are, the more vitamins are destroyed. Moreover, the leftovers must be heated again before eating, which is equivalent to losing some vitamins again. In addition to the loss of vitamins, leftovers also produce nitrite, which is bad for health.

　　 ④ thicken? That is, before cooking out of the pan, add a small amount of water starch. The role of thickening is to thicken the vegetable soup and stick it to the vegetables, and eat them together, so as not to waste the vitamins and minerals dissolved in the soup. In addition, thickening has a certain protective effect on vitamin C. However, there are pros and cons. Vegetable soup also contains more fat, table salt, nitrite and possible pesticide residues. Therefore, whether to thicken (or eat vegetable soup) depends on the specific circumstances (the variety of dishes, the amount of oil and salt used, the health status of diners, etc.).

　　⑤ Add vinegar? Vitamin C and most other vitamins are relatively stable under acidic conditions and are not easily destroyed. Adding vinegar also promotes the absorption of minerals such as calcium and iron.

　　⑥Try to eat as raw as possible? Try to eat raw vegetables or boil them in cold water. Any method of heating cooking will destroy vitamins that are unstable when exposed to heat, so from a nutritional point of view, eating raw vegetables has certain benefits. Of course, cooked vegetables also have advantages, such as improving the absorption and utilization of carotenoids and vitamin K; improving the utilization of calcium and magnesium in vegetables; softening vegetables and making them easy to digest; and greatly increasing the number of vegetables eaten; More hygienic, heat can kill germs and eggs. In general, vegetables are eaten raw and cooked, and can be determined according to the characteristics and safety of various vegetables. You don’t have to be obsessed with eating raw or squeezing juice.

　　 3. Beware of nitrite

　　Vegetables absorb nitrogen in the nitrogen fertilizer or soil, and will accumulate non-toxic nitrate. Under certain conditions (such as bacterial action or self-enzymatic action), nitrate is easily converted into nitrite. Nitrite can synthesize nitrosamine with protein decomposition products (this reaction is easy to carry out in the stomach). Nitrosamine has a certain carcinogenic effect, which can cause digestive tract cancer, such as gastric cancer. Many experts warn that nitrite in vegetables is likely to be more harmful than pesticides.