Changes in physicochemical characteristics and oxidative stability of pre- and post-rigor frozen chicken muscles during cold storage.

The objective of this study was to investigate the effects of rigor state on physicochemical characteristics and the oxidative stability of chicken leg and breast muscles as a function of freezing time. Breast and leg muscles were excised from 24 broiler chickens at 30 min or 1.5 h postmortem (PM), frozen overnight at - 75 °C immediately, and then stored at - 20 °C for 90 days to measure the meat quality traits. Results showed that longer freezing led to deterioration of meat quality with higher deterioration for post-rigor frozen muscles. Pre-rigor frozen muscles had higher pH, water holding capacity (around 90%), and sarcomere length with a lower thaw and cook loss than post-rigor frozen muscles. The Warner-Bartzler shear force (WBSF) values for chicken leg and breast muscles were insignificant (except pre-rigor leg muscles which had significantly higher WBSF value only at 90th day of storage). The lightness (L*) value increased significantly with increasing storage for all samples. Post-rigor muscles had significantly higher TBARS values (0.62 mg MDA/kg) than the pre-rigor muscles. The leg muscles had better physicochemical characteristics compared to breast muscles, except for the cook loss. Therefore, immediate freezing (prior to onset of rigor) could be an effective way to minimize the quality deterioration of frozen chicken muscles.