Protease activity and the ultrastructure of broiler chicken PSE (pale,soft, exudative) meat |
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Authors: | Allan E. Wilhelm,Magali B. Maganhini,Francisco J. Herná ndez-Blazquez,Elza I. Ida,Massami Shimokomaki |
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Affiliation: | 1. Graduate Program in Food Sciences, Department of Food Science and Technology, Londrina State University, Londrina, P.O. Box 6001, CEP 86051-990, Londrina, PR, Brazil;2. Surgery Department, Faculty of Veterinary Medicine and Animal Sciences, University of São Paulo, CEP 05508-000, São Paulo, SP, Brazil |
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Abstract: | The biological cause of broiler PSE meat seems to be an excessive release of Ca2+, promoted by a genetic mutation of ryanodine receptors located in the sarcoplasmic reticulum of skeletal muscle cells. Excessive Ca2+, associated with protein denaturation in meat, enhances protease activity and influences the functional properties of PSE meat. Twenty-four-hour post-mortemPectoralis major m. samples exhibited lower values for pH, water-holding capacity, and shear force than did control samples, in contrast to colour (L∗) and cooking loss values. Protease activity, measured as myofibril fragmentation index, presented higher values in PSE meat than in control samples. Ultrastructural examination revealed shrinking and depolymerisation of myofilaments and Z-lines disorganisation within the sarcomere in PSE meat. Intense calpain activity was also observed, indicating that the process may initiate at the filaments, because of protein denaturation, and spread through Z-lines, resulting in the collapse of the sarcomere structure. |
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Keywords: | Myofibril fragmentation index Shear force values Calpain system |
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