Effect of multiple freeze‐thaw cycles on protein and lipid oxidation in rabbit meat

Abstract

SummaryFrozen storage is chosen to be the preferred method in meat preservation. However, multiple freeze‐thaw (F‐T) cycles will occur during the transfers or distribution processes under poor cold‐chain conditions. This study investigated the effects of multiple freeze‐thaw (F‐T) cycles on water mobility, microstructure damage, protein oxidation and lipid oxidation in rabbit meat during seven F‐T cycles through 56 days. Scanning electron microscopy results indicated that the increase of F‐T cycles induced the rupture of endomysia and the increase of gaps between fibres. Low‐field nuclear magnetic resonance (LF‐NMR) results showed that the peak area of T21 and T22 decreased with increasing number of repeated F‐T cycles, indicating that immobile water shifted to free water, and free water mobility increased. During repeated freeze‐thaw process, the peroxide value, thiobarbituric acid‐reactive substances, non‐haem iron content and carbonyl groups of rabbit meat gradually increased, whereas haem content, haem iron content and sulfhydryl content of rabbit meat gradually decreased. In addition, the results of Fourier transform infrared, sodium dodecyl sulphate polyacrylamide gel electrophoresis, and intrinsic fluorescence spectroscopy indirectly proved that multiple F‐T cycles could cause α‐helix structure disruption, protein aggregation and degradation, and tryptophan oxidation of rabbit meat myofibrillar protein (MP). Overall, multiple repeated F‐T cycles changed moisture migration, damaged microstructure and promoted lipid and protein oxidation of rabbit meat.