Effect of prolonged cooking at low temperatures on the eating quality of Tibetan pork: meat quality, water distribution, and microstructure

Abstract

Abstract Tibetan pigs inhabit the plateau regions and engage in extensive exercise. Their meat is firm and less palatable, and appropriate cooking conditions can improve the flavor of the meat. This study aimed to explore the impact of cooking temperatures and times on the cooking loss rate, moisture content, tenderness, and color of Tibetan pork to elucidate their effects on the eating quality of this meat. The results indicated a negative correlation between temperature and moisture content, which decreased from 72% to 65% as the temperature increased. Meanwhile, the oxidation of myofibrillar proteins substantially increased with cooking temperature and time, resulting in a gradual augmentation of the cooking loss and shear force of the pork. The migration of bound water and the release of free water from the pork were faster after treatment at 80 °C compared with 50 °C. The results of infrared spectroscopy suggested that prolonged cooking led to the conversion of α-helix into β-sheet in the secondary structure of myofibrillar proteins. The microstructures observed through scanning electron microscopy exhibited a gradual degradation of connective tissues in the muscles at high temperatures, and the fiber structure of the muscles became more condensed and granular, blurring the textural appearance of the muscles. These results indicated that prolonged cooking time at a low temperature (steaming for 6 h at 50°C ) was conducive to the optimal tenderness of Tibetan pork. This study provides a theoretical basis for improving the meat quality of Tibetan pork products and developing more rational processing methods.