Everyone likes to keep food fresh in the refrigerator. Not all foods can be put in the refrigerator, especially the following common foods. After tomatoes are frozen at low temperature, the flesh of tomatoes is blistered, soft and rotten, or cracked, with black spots on the surface, immature and tasteless, and even rotten in severe cases. Bananas stored below 12 will turn black and rot. Fresh Litchi If Litchi is left at 0℃ for one day, the skin will turn black and the pulp will turn sour. After the chocolate is put into the refrigerator, once it is taken out, it will form a layer of frost on the surface at room temperature, which is easy to go moldy and deteriorate and lose its original flavor. Ham If ham is kept in the refrigerator at low temperature, the water in it will freeze, the fat will precipitate, the ham meat will agglomerate or loosen, and the meat will become stale and perishable. Bread: In the baking process, the linear segment of starch in flour has aged, which is the reason why bread has elastic and soft structure. With the extension of storage time, the linear part of amylopectin in bread slowly associates, which makes the soft bread gradually harden. This phenomenon is called "aging". The aging rate is related to temperature. At low temperature (above freezing point), bread will age faster, but after being put in the refrigerator, the degree of hardening will come faster. Fish in the refrigerator should not be stored for too long. The refrigeration temperature of household refrigerators is generally-15, and the best refrigerators can only reach -20. However, when the storage temperature of aquatic products, especially fish, is lower than -30℃, fish tissues will be dehydrated or undergo other changes. For example, crucian carp will be prone to rancidity, and its meat quality will change and it cannot be eaten. Therefore, fish stored in the refrigerator should not be kept for too long. Frozen vegetables stored for a long time will not only change color, lose nutrition and decrease quality, but also rot easily and become inedible. Frozen meat, frozen fish, frozen chicken and frozen duck, their tissues and cells will be destroyed by the crystallization of water. Once thawed, a large amount of protein will ooze from the damaged tissues and cells and become food for bacteria to multiply. The experiment shows that the fresh mackerel frozen 1 day will rot faster 1 times than fresh fish if it is stored at 30 for 6 hours. After thawing, the number of bacteria increased by about 2 times when the yolk was kept at 18 for 2 hours. After 8 hours, 1 vegetables will turn yellow quickly, and vitamin C will be easily destroyed. When vegetables are stored at 20℃, the decomposition loss of vitamin C is twice that at 6~8℃. Don't put Chinese medicine in the refrigerator. If the medicinal materials are put in the refrigerator and mixed with other foods for a long time, not only are all kinds of bacteria easy to invade the medicinal materials, but they are also easy to get wet and destroy the medicinal properties of the medicinal materials. Therefore, for some precious medicinal materials, such as ginseng, velvet antler, gastrodia elata, codonopsis pilosula and so on. If it needs to be preserved for a long time, you can put it in a clean glass bottle, then add a proper amount of glutinous rice fried to dark yellow with slow fire, and cover the bottle cap. Cucumber and green pepper: Cucumber and green pepper will be frozen and "injured" if they are kept in the refrigerator for a long time-turning black, soft and stale. Cucumbers also have sticky hairs. Because the storage temperature in the refrigerator is generally around 4 to 6, the suitable storage temperature of cucumber is 10 to 12, and that of green pepper is 7 to 8. So it shouldn't last long. Leafy vegetables are perishable after cold storage. Freshly squeezed juice is easy to destroy its vitamins and other nutrients after freezing!