Oil: When the oil temperature is above 200℃ when cooking, it will produce a harmful gas called "acrolein". It is the main component of lampblack, and it will also produce a large number of highly carcinogenic peroxides. Therefore, it is best to use 80% hot oil for cooking.
Soy sauce: Cooking soy sauce at high temperature for a long time will destroy its nutrients and lose its flavor, so put soy sauce before cooking.
Salt: when cooking with soybean oil and rapeseed oil, in order to reduce the loss of vitamins in vegetables, salt should generally be put after cooking; Stir-fry with peanut oil, because peanut oil is easily polluted by Aspergillus flavus, put salt in the wok first; When cooking with meat oil, you can first put half of the salt to remove the residual organochlorine pesticides in the meat oil, and then put the other half of the salt; When cooking meat dishes, in order to make the meat tender, it is best to fry it until it is 80% ripe and add salt.
Vinegar: If you add a little vinegar after cooking vegetables, you can reduce the loss of vitamin C in vegetables, promote the dissolution of mineral components such as calcium, phosphorus and iron, and improve the nutritional value of dishes and the absorption and utilization rate of human body.
Cooking wine: when cooking meat dishes such as fish and sheep, put some cooking wine to remove the fishy smell through evaporation of cooking wine. Therefore, the best time to add wine should be when the temperature in the pot is the highest when cooking. In addition, add wine after frying shredded pork; Add wine after the grilled fish is fried; It is best to add wine after fried shrimp is cooked; Soup is usually boiled and stewed with low fire, and wine is put when simmering.
Monosodium glutamate: When monosodium glutamate is heated above 120℃, it will become sodium glutamate, which is not only tasteless, but also toxic. Therefore, it is best to add monosodium glutamate when frying.
Sugar: When making sweet and sour fish and other dishes, sugar should be put first, and then salt should be added, otherwise the "dehydration" of salt will promote the solidification of protein, making it difficult for people to fully understand the taste of sugar, which will lead to sweetness on the outside and light on the inside, affecting its delicacy.