Effects of Different Salting Methods on the Quality Traits, Histomorphology and Protein Structure of Cooked Pork Steaks

The aim of this study was to investigate the effects of different salting methods (wet salting, dry salting, ultrasonic assisted wet salting) on quality traits (color, texture, water retention capacity), histomorphology and protein structure of cooked pork steaks. Longissimus thoracis et lumborum (LTL) muscles of pork were selected as experimental material, and the meat samples were salted by different methods and then cooked. Meat quality, water distribution, histomorphology, protein surface hydrophobicity and protein secondary structure of cooked meat were determined. The results showed that different salting methods had significant influences on the quality traits of cooked pork steaks. In comparison with the other two salting methods, the sample salted by ultrasonic had the lowest cooking loss, the highest redness value, and the highest viscosity and tenderness. The results of water distribution showed that the longitudinal (T₁) and transverse (T₂) relaxation intensity were the highest in samples of ultrasonic assisted salting. Meanwhile, the transverse relaxation time was the longest in cooked samples of ultrasonic-assisted salting, the proportion of immobilized water was the highest, and the proportion of free water was the lowest. Ultrasonic assisted salting increased muscle fiber swelling, and individual myofibers in the salted tissue could be discerned, perhaps due to the degradation of connective tissue during salting. Additionally, the cooked meat samples of ultrasonic assisted salting had the strongest protein hydrophobicity ability. Protein secondary structure analyses showed that the meat samples in ultrasonic assisted salting group exhibited the lowest content of α-helix and β-turn, and the highest content of β-sheet and random coil, indicating the highest degree of protein unfolding. Moreover, protein structural changes in cooked meat were significantly correlated with meat quality traits.