Effects of freezing methods and frozen storage on physicochemical, oxidative properties and protein denaturation of porcine longissimus dorsi

Changes in physicochemical properties, oxidative properties, and protein denaturation of porcine longissimus muscles, which were frozen by different methods and then stored at-18 degrees C for various times, were investigated. As the freezing rate was increased, the deterioration was reduced. In addition, over a period of 168 d, the quality reduction was proportional to the levels of oxidation and protein denaturation. The obtained results showed that a slower freezing rate and long-term duration had a negative influence on the porcine quality. At 168 d, although the thawing loss, total volatile base nitrogen, and electrical conductivity of the-40 degrees C frozen samples were higher than those of the-80 degrees C and liquid nitrogen frozen samples, they remained within the acceptable limits. However, compared with freezing at - 18 degrees C, freezing at-40 degrees C reduced oxidation, and maintained the sample thermal stability and viscoelasticity. Therefore, in terms of energy conservation, freezing at-40 degrees C could preserve porcine quality over 168 d, thereby confirming its suitability for application in the meat industry.