Effect of multiple freeze–thaw cycles on the quality of chicken breast meat

The objective of this study was to determine the effects of repeated freeze–thaw cycles (0–6) on any physico-chemical changes and lipid and protein oxidation in chicken breast. The results showed that meat colour, a∗ (redness) and b∗ (yellowness) values decreased while L∗ values (lightness) increased with increasing cycle numbers. Increasing freeze–thaw cycles resulted in a greater degree of lipid and protein oxidation, as evidenced by higher contents of malondialdehyde and carbonyl compounds, and lower contents of sulfhydryl groups. Differential scanning calorimetry profiles and SDS–PAGE banding patterns of myofibrillar proteins indicated slight denaturation of myosin and actin with repeated freeze–thaw cycles. The structural changes occurring in proteins caused by oxidation directly affected the ability of muscles to retain water, as confirmed by the nuclear magnetic resonance relaxometery profile. In conclusion, multiple freeze–thaw cycles increased lipid and protein oxidation and decreased water holding capacity and colour stability of broiler chicken breast.