title: The roles of the actin-myosin interaction and proteolysis in tenderization during the aging of chicken muscle.
abstract: The objective of this study was to investigate the contribution of the changes in the actin-myosin interaction and proteolysis on meat tenderization during postmortem storage. Following slaughter, chicken breast muscles were removed and stored at 4°C. Changes in the actin-myosin interaction over 48 h of aging were determined by monitoring the Mg(2+)- and Ca(2+)-ATPase activities. Shear force values, pH, protein degradation, calpain activities, and myofibrillar ultrastructures were also investigated. Results showed that the initial weak actin-myosin interaction strengthened at 12 h postmortem followed by a gradual weakening, which was supported by a decrease in Mg(2+)-ATPase activities and a lengthening of the sarcomeres. According to SDS-PAGE and Western blotting analyses, the 30-kDa troponin-T fragment could not be readily detected until 12 h, whereas, at the same time, desmin had been rapidly degraded. However, there was a gradual decline in μ-calpain activity, commencing after about 6 h. Meanwhile, the largest decline in shear force was observed between 12 and 24 h postmortem. These findings suggest that weakening of the strong actin-myosin interaction formed at rigor may play a large role in meat tenderization during the early period of storage. It is proposed that weakening of the actin-myosin interaction results in lengthening of the sarcomeres, and then activated calpains are more able to reach their targeted sites, enabling proteolysis. These 2 factors may be involved in the conversion of muscle to tender meat during postmortem storage.
authors.affiliation: Key Laboratory of Meat Processing and Quality Control, Ministry of Education, College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: S
authors.initials: S
authors.lastname: Li
authors.forename: X
authors.initials: X
authors.lastname: Xu
authors.forename: G
authors.initials: G
authors.lastname: Zhou
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western / Q000662:veterinary; D002154:Calpain / Q000378:metabolism; D002645:Chickens / Q000378:metabolism*; D003893:Desmin / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel / Q000662:veterinary; D008297:Male; D008460:Meat / Q000592:standards*; D018482:Muscle, Skeletal / Q000378:metabolism*; D009210:Myofibrils / Q000378:metabolism; D009218:Myosins / Q000378:metabolism*; D011180:Postmortem Changes; D059748:Proteolysis; D013997:Time Factors; D020107:Troponin T / Q000378:metabolism
chemical_list: D000199:Actins; D003893:Desmin; D020107:Troponin T; D002154:Calpain; D009218:Myosins