The texture is an important indicator for evaluating meat products, and there are many related studies. As early as the 1950s, studies have shown that comparing roasted beef for up to 43 hours at a temperature of 80°C and roasted beef for 1/3 of 43 hours at a temperature of 80°C by a cooker, it was found that the former beef is more tender. Christensen and others selected bovine semitendinosus muscle and controlled the heating temperature to be 53℃, 55℃, 58℃, 63℃) and heating time to be 5 and 7 hours, and found that the toughness of cooked beef can be reduced at the heating temperature approached 60℃ and the heating time greater than 4℃. The study also found that the reduction of shear force is caused by the weakening of connective tissue, and the solubilization of collagen fibers may be related to cathepsin activity.
 
Botinestean and others also selected bovine semitendinosus, and set the heating temperature to 60 ℃ and 70 ℃ by low-temperature slow cooking; the heating time was 4.5 hours. They concluded that the hardness and chewiness of sous vide cooking were lower under the heating condition of 60℃. The appearance is also more beautiful. Not only beef but mutton and pork are suitable for low-temperature slow cooking. Christensen used the longissimus muscle and semitendinosus muscle of pork as raw materials to study the shear force of pork under different heating temperatures such as 48℃, 53℃, 58℃ and 63℃ and heating times such as 0 hour, 5 hours and 17 hours. When the heating temperatures are between 53 to 58°C, the toughness of the meat is bad, and the cooking time of older pork needs to be extended. Usually, the ideal tenderness can be achieved by heating for 5 hours.
 
Becker and others extended the heating time to 10, 20 and 30 hours and further concluded that the texture of cooked meat did not change after the heating time exceeded 30 hours. Roldan selected the longissimus muscle of mutton, and controlled the heating temperatures to be 60, 70 and 80℃) and heating times 6, 12 and 24 hours); concluded that the shear force gradually decreased with the prolongation of time. We've learned in some excellent research that the age of an animal has a great impact on the quality of the meat. Young bull beef can be heated at 50 to 53°C for less than 4 hours to reduce shear force and adhesion; veal or cow beef of 2 to 17 years old needs to be heated at temperatures of 55 to 65 °C for 8 to 24 hours to improve tenderness. For older female pork, increasing the heating temperature to 48 to 63℃) or prolonging the heating time to 5 to 17 hours did not significantly improve the quality of the meat. On the contrary, when heating small pork under the same conditions, tenderness can be obtained. Some people have attempted to explain the role of connective tissue in low-temperature cooking, but studies have found a greater association between connective tissue and muscle locations and ages, while collagen plays a greater role in longer cooking due to protein denaturation and other reasons. The analysis of shear force changes in cooked meat cannot be directly attributed to connective tissue.