Influence of different thawing methods on physicochemical changes and protein oxidation of porcine longissimus muscle

The objective of the present study was to elucidate the physicochemical changes and protein oxidation of porcine longissimus muscle as influenced by different thawing methods. Five kinds of thawing methods, comprising of refrigerator thawing (RT, 4 degrees C), ambient temperature thawing (AT, 20 degrees C), water immersion thawing (WT, 14 degrees C), lotic water thawing (LT, 9 degrees C), and microwave thawing (MT), were used. There were significant effects on the porcine meat quality due to different thawing methods. RT had the least quality loss and the physicochemical characteristics of pork were closer to fresh muscle than the other thawing methods. MT significantly increased thawing loss, cooking loss, cutting force, carbonyl content, and TBARS (thiobarbituric acid-reactive substances) value, but decreased a* value and Ca-, K-ATPase activities (P < 0.05). Microstructural changes in experimental muscle showed that MT induced visibly larger gap between muscle fibers and tore more muscle fiber bundles compared to the other thawing methods. The reduction of Ca- and K-ATPase activities (P < 0.05) of myofibrillar protein was consistent with the increases in carbonyl content and TBARS value (P < 0.05). The results demonstrated all the thawing methods could cause porcine lipid and protein oxidation. Gel electrophoresis patterns of porcine muscle displayed that different thawing methods did not induce obvious protein aggregates and fragments. (C) 2011 Elsevier Ltd. All rights reserved.