Stages of Meat Transformation
In order to understand the differences between chilled meat, hot fresh meat, and frozen meat, we must first understand the transformation process of meat. All meats go through several stages of rigor, maturation, autolysis, and putrefaction after slaughtering and death.
Rigor Stage
Meat that has just been slaughtered is weakly alkaline. At this stage, enzymes in the animal's muscle tissue continue to act, breaking down glycogen and phosphorus-containing organic compounds in the muscle into lactic acid and free phosphoric acid, increasing the acidity of the meat. When the acidity reaches a certain level, muscle fibers appear, resulting in poor taste and cloudy broth.
Maturation Stage
After the rigor stage, enzymes in the meat continue to act, breaking down meat proteins and oxidizing fats. The connective tissues become softer and have a certain elasticity, making the meat tender and fragrant. This is the "maturation" of meat, also known as "acid discharge" in the slaughtering industry. During maturation, a glossy film is formed on the surface of the meat due to protein coagulation, which prevents microorganisms from invading the interior. In addition, the lactic acid formed in the muscle has a certain bactericidal effect on bacteria and viruses.
The speed of meat maturation depends on the environmental temperature and the quality of the meat. The higher the ambient temperature, the faster the maturation process. Generally, the maturation process can be completed in 1-3 days at 4 degrees Celsius. For pork, beef, and mutton, the maturation process at room temperature takes about 6-8 hours, while for poultry like chicken, it takes 4-6 hours. Due to the tender muscle fibers, fish takes about 2 hours.
Autolysis and Putrefaction Stage
If slaughtered meat is stored at room temperature for a long time after maturation, the enzymes in the tissue continue to act, breaking down proteins and fats, causing the meat to undergo autolysis and creating conditions for the invasion of bacteria and other microorganisms. Eventually, the meat becomes putrefied, changes in color and odor occur, and it loses its edible value.
Differentiation of Meat in the Market
Hot Fresh Meat
Hot fresh meat refers to freshly slaughtered meat that is put on the market early in the morning without any cooling treatment. It is the fresh meat we commonly find in general markets. This type of meat is transported and sold at room temperature, requiring a relatively short maturation time. Additionally, it is susceptible to contamination during transportation and sales, making it easier for microorganisms to multiply. Therefore, it has a shorter shelf life.
Chilled Meat
Chilled meat, also known as cooled meat, refers to fresh meat from slaughtered animals that is rapidly cooled and kept at a temperature of 0-4 degrees Celsius throughout the subsequent processing, distribution, and sale process, strictly following the quarantine regulations. Since chilled meat is always kept at a low temperature during transportation and sales, the growth and reproduction of microorganisms are effectively inhibited, extending its shelf life. The entire process from handling to sale of chilled meat takes about two days, allowing the meat to naturally mature. Therefore, chilled meat has a good taste, freshness, and can be cooked directly without thawing, reducing the loss of nutrients during thawing. Chilled meat is generally sold in supermarkets and markets with refrigeration conditions, and the transportation and sales costs are higher, resulting in higher prices compared to hot fresh meat.
Frozen Meat
Frozen meat is fresh meat that has been sent to a freezer and rapidly frozen, typically below -18 degrees Celsius. Although frozen meat has fewer bacteria and is relatively safe to consume, it needs to be thawed before consumption, which can lead to the loss of nutrients and a less tasty flavor compared to fresh meat, not to mention the taste of chilled meat.
Choosing Meat
After comparing the three types of meat mentioned above, we can conclude that in terms of:
Safety: Frozen meat > Chilled meat > Hot fresh meat
Nutrition: Chilled meat > Hot fresh meat > Frozen meat
Maturation: Hot fresh meat > Chilled meat > Frozen meat
Price: Chilled meat > Hot fresh meat > Frozen meat
Therefore, when conditions allow, it is recommended to choose chilled meat. In foreign markets, the market share of chilled meat has already exceeded 90%. China is also promoting the market for chilled meat, with a current market share of around 25%, while hot fresh meat is more common.
Tips for Buying Meat
1. The hot fresh meat we usually buy in the morning has usually been stored at room temperature for a long time and has undergone maturation. This meat can be directly cooked into dishes with a good taste. If you need to store it, it should be placed in the refrigerator at a temperature below 4 degrees Celsius, but it should not be stored for too long.
2. The maturation time for fish meat is relatively short, so it can be cooked immediately after purchase.
3. To ensure the nutritional value and taste of stored meat, it is recommended to consume the purchased meat within one week when stored in the refrigerator.
