Integrated volatilomics and metabolomics reveal the meat quality changes of Hu sheep biceps femoris during refrigerated and frozen storage

The quality of mutton deteriorates during storage, yet the underlying mechanisms under different conditions remain to be fully elucidated. This study investigated the quality changes in Hu sheep biceps femoris during refrigerated (4°C for 0, 2, 4, 6, and 8 days) and frozen (-20°C for 0, 1, 3, 6, and 9 months) storage by analyzing meat quality, lipid oxidation, protein oxidation, redox parameters, volatile flavor substances and metabolites. Results showed that prolonged storage significantly decreased meat quality ( P < 0.05), driven by intense lipid and protein oxidation. On day 8, the levels of malondialdehyde and protein carbonyl groups were 3.15 times and 1.86 times higher than on day 0 ( P < 0.05). After 9 months of freezing, these two substances reached 7.68 times and 2.09 times the levels observed on day 0 ( P < 0.05). This oxidative damage coincided with a compromised antioxidant capacity. Hexanal and dimethyl sulfide were identified as key volatile compounds in refrigerated and frozen storage. Differential metabolites were enriched in amino acid metabolism during refrigeration and lipid metabolism during frozen storage, showing significant correlations with key volatiles. These findings enhance the understanding of temperature and time effects on mutton quality during refrigerated and frozen storage. • We revealed the changes in meat quality of biceps femoris in cold chain mode. • Hexanal and Dimethyl sulfide increased significantly in cold chain storage. • Amino acid metabolism and lipid metabolism were key pathways. • The key volatile compounds and metabolites exhibited significant correlations.