Relationship between water-holding capacity and protein denaturation in broiler breast meat

The objective of this study was to determine the relationship between water-holding capacity (WHC) attributes and protein denaturation in broiler breast meat. Boneless skinless breast fillets (n = 72) were collected from a commercial processing plant at 2 h postmortem and segregated into low-WHC and high-WHC groups based on muscle pH and color (L*a*b*). At 6 and 24 h postmortem, brine uptake (%), cooking loss (%), and protein solubility (sarcoplasmic and myofibrillar) were measured and protein fractions were analyzed using SDS-PAGE. Drip loss accumulation (%) was measured after storage for 2 and 7 days postmortem. High-WHC fillets exhibited lower L*-lightness values and greater pH values at 2 and 24 h postmortem than low-WHC fillets. High-WHC fillets had greater brine uptake and less cooking loss at both 6 and 24 h postmortem compared to low-WHC fillets. Aging from 6 to 24 h postmortem increased brine uptake in high-WHC fillets, but did not affect cooking loss in either low-WHC or high-WHC fillets. Drip loss accumulation was greater in low-WHC fillets at both 2 and 7 days postmortem. Myofibrillar protein solubility decreased with postmortem time but was not different between low-WHC and high-WHC fillets. Sarcoplasmic protein solubility increased with postmortem time and was greater in high-WHC fillets. SDS-PAGE analysis indicated that low-WHC fillets exhibited more glycogen phosphorylase denaturation than high-WHC fillets as evidenced by a more extensive shift of the protein from the sarcoplasmic to the myofibrillar protein fraction. Correlation analysis revealed that overall protein solubility measurements were not related to WHC attributes but that the degree of glycogen phosphorylase denaturation was significantly correlated (|r| = 0.52 to 0.80) to measures of WHC. Data indicated that WHC differences in broiler breast fillets were not due to differences in myofibrillar protein denaturation and suggested that the denaturation of sarcoplasmic proteins onto myofibrils may influence WHC in breast meat.