The temperature of low-temperature cooking is usually lower than 100℃ and the longest heating time is 48 hours. As early as 1974, slow cooking first emerged as a new cooking technology. Davey and others used low-temperature slow cooking to heat beef and significantly improve its texture. Under different heating conditions of meat, the texture, color and flavor of the meat will be affected to varying degrees. The digestibility will also be improved. Different heating rates and heat transfer rates can change the rate of change in digestibility, and comprehensively affects the taste of meat after cooking. For consumers, tenderness, juiciness, color, flavor and food safety are all important factors that affect their purchasing choices. Therefore, while ensuring food safety, improving the sensory quality of meat has become a key factor in the meat industry. Low-temperature cooking appears just in time. Sous-vide cooking is one of the main cooking methods, which refers to the heating technology of vacuum sealing the ingredients in vacuum packaging bags and heating them with water or steam as the heating medium.
 
In the heating process of meat products by a sous-vide cooker, when the core temperature reaches above 40℃, the protein begins to denature, and the protein structure gradually shrinks as the temperature increases; when the core temperature reaches 50 to 60℃, the diameter of the muscle fiber will be greatly reduced. When the temperature reaches above 60℃, the myofibrils will start to contract longitudinally at the same time, and the contraction speed gradually decreases with the continuous increase of the heating temperature. The diameter contraction of myofibrils is caused by the degeneration of myofibrillar proteins, followed by a dramatic contraction of collagen. Compared with temperature increases, the prolonged heating time has a milder effect on meat texture. Christensen and others compared quality changes of pork longissimus under two conditions of increased temperatures such as 53°C, 55°C, 57°C and 59°C and prolonged heating time from 3 to 20 hours), and found that the changes under prolonged heating time were not obvious. In the heating process, the meat also undergoes severe longitudinal shrinkage, but compared with high-temperature heating, low-temperature slow cooking can control the longitudinal shrinkage within a limited range. The reason may be that the presence of some heat-resistant protein hydrolase in the meat affects the meat's water holding capacity and cooking losses. Kristensen had hypothesized that proteolytic enzymes degrade the cytoskeleton, thereby, increasing the cell's water holding capacity.
 
In recent years, Zeng has observed degraded desminin and actinin accompanied by various proteases, indicating that the swollen single-fiber cytoskeleton improves the water holding capacity of myofibrils. However, even if the cooking temperature is much lower than the actual denaturation temperature, the protein will still be denatured after prolonged heating. Although the direct relationship between changes in muscle volume and the toughness of cooked meat is unclear, certain structural changes in meat after heating do affect the tenderness of the final product. When the heating temperature is kept between 50 and 65°C, the contraction of myofibrils makes the connective tissue around the fascia more easily broken, while the toughness of the myofibrils changes less. At higher heating temperatures, muscle connective tissue degeneration tends to soften, while myofibril toughness increases.