Effect of Different Freezing Methods on the Cooking Quality of Pork

To investigate the effect of different freezing methods on the cooking quality of pork, porcine Longissimus dorsi muscle frozen by three different methods: air freezing (AF), immersion freezing (IF) and ultrasonic-assisted immersion freezing (UIF) were stewed after being thawed at 4 ℃ , and their moisture content, cooking loss, shear force, color, volatile flavor components and taste were analyzed. Fresh (unfrozen) meat was used as control. The results showed that the moisture content of cooked UIF meat (57.81%) was significantly higher than those of cooked AF and IF meat, which was the closest to that of the control group, and the cooking loss was less than that of any other treatment group. The shear force of the UIF group was the smallest and slightly lower than that of the control group, indicating that ultrasound had a positive effect on the tenderness of cooked pork. There was no significant different in brightness between the control and UIF groups. Principal component analysis (PCA) of the electronic nose sensor responses for volatile flavor compounds showed that the first and second principal components accounted for 98.346 0% and 1.317 4% of the total variance, respectively. Linear discriminant analysis (LDA) of the electronic tongue data showed that the UIF group was not significantly differentiated from the control group and they were similar in taste, indicating that ultrasound slowed down the quality and flavor deterioration of frozen pork and brought its quality closer to that of fresh meat.