Today, meat can be divided into fresh meat, cold meat and frozen meat. And fresh meat, that is, "hot fresh meat", refers to the meat that is slaughtered first and sold now without any cooling treatment. Frozen meat is the meat stored in the cold storage room at minus 18 degrees. The reason why people don't like chilled meat so much is that many people confuse chilled meat with chilled meat in their traditional ideas. In fact, cold meat is superior to fresh meat and frozen meat in taste and nutrition preservation. "Cold meat", also known as chilled meat, sour meat and fresh water meat, refers to the strict implementation of the veterinary inspection system and the rapid cooling treatment of slaughtered livestock carcasses, which can effectively inhibit the growth and reproduction of microorganisms within 24 hours. The production of cold meat requires very strict environmental temperature and workplace hygiene conditions, and the slaughtering and processing industry needs to reach the management level of hazard analysis and critical control points. Cold meat absorbs the advantages of hot meat and frozen meat, and eliminates the disadvantages of both. Then, why is cold meat also called sour meat? This is because a series of changes will take place in the meat after slaughter, and the process of rigidity, thawing and softening will appear one after another, which will make the meat soft and juicy and produce unique taste and smell. The process of softening and improving the flavor of meat is called meat ripening in the industry, and it is called meat acid removal in the industry. This process is usually carried out at low temperature, also called cooling acid removal. The process of acid discharge makes cold meat have these characteristics. Under the cooling temperature of zero to four degrees for a long time, the activity of enzymes and the growth and reproduction of most microorganisms are inhibited. When the temperature is 3℃, the pathogenic bacteria stop reproducing, and Botulinum botulinum and Staphylococcus aureus no longer secrete toxins, thus avoiding meat spoilage and ensuring the safety and hygiene of meat. A layer of dry oil film is formed on the surface of chilled meat in a cooling environment, which can reduce water evaporation and prevent microorganisms from invading and reproducing on the surface of meat. The delay in maturity makes the fiber structure of muscle tissue change, making it easier to chew and digest, and the absorption and utilization rate is also high. In the process of acid excretion, adenosine triphosphate, a nucleoprotein, is decomposed and finally produces phosphoric acid and hypoxanthene. Therefore, cold meat is more nutritious, soft and elastic in texture, tender and juicy, delicious in taste, fragrant in smell, easy to chew, and more conducive to human absorption of nutrients. The general sense of fresh meat, that is, hot meat, is usually slaughtered the night before, and some are slaughtered in the early morning and listed in the morning, during which time there is no cooling treatment. In the process of processing, transportation and sales, it is inevitable to be polluted by bacteria, viruses, insects, vehicles and packaging in the air. In addition, due to the relatively high temperature environment, bacteria will multiply in large numbers, which has potential safety hazards. Frozen meat is to immediately send the slaughtered fresh meat into the freezer for rapid freezing, generally below MINUS 18 degrees. Although frozen meat has fewer bacteria and is safe to eat, it needs to be thawed when eating, which will lead to the loss of nutrients, and its taste is not as good as that of fresh meat, let alone catch up with the taste of cold meat. It is understood that developed countries began to promote the consumption of chilled meat as early as the mid-20th century. At present, chilled meat has accounted for about 90% of the market share in Europe and America. Although eating chilled meat is a kind of consumption progress, there are still some problems in eating, buying and preserving chilled meat. Some people are not good at eating and preserving chilled meat. They buy a large amount at a time and throw it into the refrigerator when they can't finish eating it. This turned the chilled meat into frozen meat and lost its value. Others want to buy cold meat with no brand or unknown small brand in small shopping malls, which is difficult to guarantee that it is real cold meat. Experts remind that the price difference between cold meat and fresh meat on the market is not too big now. It is best to go to the counter and choose big brand products to buy cold meat.