LAUSR

Postmortem changes of sarcoplasmic and myofibrillar protein phosphorylation in pectoralis major (PM) muscle of broilers under pre-slaughter stress were investigated. Broiler chickens were randomly distributed to unstressed control and transport under high environmental temperature groups. PM muscle samples of transport-stressed broilers were classified into normal or pale, soft and exudative (PSE)-like. Sarcoplasmic fraction in PSE-like meat had a higher global phosphorylation level than that in normal meat at the early postmortem stage. The myofibrillar proteins showed diverse phosphorylation patterns at different postmortem times. The stress-induced highly phosphorylated sarcoplasmic proteins were glycometabolic enzymes, which partially contributed to accelerated glycolysis rate. The phosphorylation levels of most sarcomeric proteins identified in the myofibrillar fraction were affected by postmortem time, implying their roles in regulating muscle rigor mortis development. This work contributes to a deeper understanding of the biochemical processes that may lead to stress-induced changes in meat quality.