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

Abstract

Summary Frozen 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.

Quality and volatile compound analysis of shrimp heads during different temperature storage

“…The b * values showed an increase and then a decrease during storage at four temperatures. As reported, there is a correlation between b * values and lipid oxidation, and free radicals and carbonyl compounds generated from oxidation of unsaturated fatty acids in shrimp heads could react with free amino acids in proteins to synthesize brown pigments ( Wang et al, 2021 ). The decreasing trend of a * and b * values in late storage may correlate with blackening.…”

“…Color is one of the most important indicators of seafood quality evaluations, and an intuitive attribute of freshness. Generally, the color of shrimp heads changes during storage due to lipid oxidation and pigment degradation ( Wang, He, Zhang, Chen, & Li, 2021 ). As shown in Table 1 , L * values gave a trend of decrease followed by an increase during storage period, probably due to the action of polyphenol oxidase (PPO), which resulted in the blackening of shrimp heads.…”

Effects of Freeze–Thaw Cycles on Water Migration, Microstructure and Protein Oxidation in Cuttlefish

“…This was due to the physical destruction of cuttlefish muscle cells by ice crystals during the F-T process and the weakening of the binding force between water and protein molecules due to protein oxidation, which caused an increase in the free water content [24]. Therefore, the control samples showed lower juice loss and poorer water holding capacity [25].…”

“…It indicates that the protein structure changes from regular to sparse [15]. During multiple freeze-thaw cycles, protein denaturation, sulfhydryl oxidation and weakening of the hydrogen bond between water and protein lead to the disruption of the protein spatial conformation [25,26,37].…”

Crystallization Behavior and Quality of Frozen Meat

“…In addition, disruption of cellular structures by large ice crystals releases oxidizing agents, such as heme and non-heme iron and membrane lipids that accelerate oxidative reactions [64,111]. In this regard, various studies have shown an increase in oxidation during freezing/thawing of meat, and subsequently the development of undesirable flavor, color, and textural changes [64,[112][113][114][115]. In particular, poultry meat is highly susceptible to oxidation than meats from other species, due to its high content of unsaturated fatty acids [116].…”