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 con-
tents 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, mul-
tiple freeze–thaw cycles increased lipid and protein oxidation and decreased water holding capacity and
colour stability of broiler chicken breast.