Abstract: Proteolysis and denaturation of porcine proteins on heating were investigated.Porcine muscles were heated to different end internal temperatures(EIT,40 ℃,50 ℃,60 ℃,70 ℃,80 ℃,90 ℃,98 ℃) for 0,10 and 20 min,respectively.Sodium dodecyl sulphate polyacrylamide gel electrophoresis(SDS-PAGE) was used to qualitatively assess the proteolysis and denatur-ation in sarcoplasmic and myofibrillar proteins of porcine muscles prepared by different heating methods.The results showed that the soluble sarcoplasmic proteins substantially decreased with increasing cooking temperature,whereas the soluble myofibrillar proteins increased below 60 ℃ and then reduced from 60 ℃ to 98 ℃.Two components of titin(34 kD and 37 kD) were thermostable proteins,the G-actin(43 kD) was less thermostable,and heavy chains of myosin degraded up to 60 ℃.Therefore EIT could be determined through the patterns of lanes by SDS-PAGE.On the other hand,different muscles of porcine were heated by various cooking methods(steam,pan fry,deep fry,baking,microwave and boiling),then the proteolysis and denaturation in sarcoplasmic and myofibrillar proteins of porcine muscles were investigated by SDS-PAGE.The results revealed that heating methods effected the proteolytic and denatural rate of porcine proteins significantly with microwave the fastest and deep fry the slowest.

Key words: porcine protein, heat treatment, sarcoplasmic, myofibrillar, SDS-PAGE