Processing and Products

S OF PAPERS 221 46 Protein extractability of breast muscle from broilers and three non commercial strains of chicken. B. M. Rathgeber*1, R. M. Currie2, K. L. Thompson1, and F. G. Silversides3, 1Agriculture & Agri-Food Canada, Kentville, NS, Canada, 2Nova Scotia Agricultural College, Truro, NS, Canada, 3Agriculture & Agri-Food Canada, Agassiz, BC, Canada. The extractability of myofibrillar proteins is a useful indicator of functional properties of chicken breast meat. Post-mortem metabolic events are influential on protein functionality and are the focus of many investigations evaluating pale meat of poor quality. The objective of this study was to investigate the protein extractability of 4 breeds of chicken subjected to 2 chilling regimens. Thirty-two males of each breed, Columbia Rock (CR), Barred Rock (BR) White Leghorn (WL) and Commercial Broilers (CB) were grown to 50 d of age and processed. The left carcass halves were immersed in ice water and the right sides were immersed in 40°C water for 4 h. The carcass halves were removed from water and air chilled at 4°C until 24 h post-mortem when a 5 g muscle sample was removed and quick frozen at −80°C. The protein content of all samples was estimated following nitrogen analysis. Samples were homogenized in low ionic strength (LIS) buffer and centrifuged. The supernatant was removed to determine proteins in solution. Following a second extraction with LIS the pellet was homogenized in high ionic strength (HIS) buffer to determine salt soluble proteins. Statistical analysis using SAS mixed model was employed. The CB breast meat had the highest (P < 0.05) level of protein (22.4%) and BR (20.7%) was higher than CR (20.3%) or WL (19.2%). The extractability of proteins in LIS was higher for CB (40.0% of total protein) than CR (35.6%) with the other breeds intermediate and not different from these. Delaying the chilling of one side reduced the extractability of proteins in LIS (P < 0.05) and the salt soluble proteins, however, the effect was less for CB. There was a 24% reduction in extractability of proteins in HIS for CB when chilling was delayed. For BR there was a 60% reduction, 53% for CR and 52% for WL. The functional properties of breast muscle proteins from non commercial chickens used in this experiment were markedly different from CB and may serve as a valuable resource for studying the mechanisms behind the development of poor quality breast meat.