Sex-Dependent Changes in Quality and Flavor-Related Chemical Profiles of Mytilus coruscus During Long-Term Frozen Storage

The effects of frozen storage on the quality and flavor of female and male Mytilus coruscus were investigated at −18 °C for 0, 90, and 150 days through analyses of physicochemical properties, free amino acids, 5′-nucleotides, fatty acids, and volatile organic compounds. Distinct sex-dependent changes were observed in the quality and flavor profiles. After 150 days, the centrifugal loss reached 1.2 and 1.5 times the fresh levels in females and males, respectively, whereas total volatile basic nitrogen reached 2.7 and 2.4 times the corresponding fresh levels. Malondialdehyde increased to approximately 3.3 times the fresh level in both sexes and was 1.7 times as high in females as in males. Males generally showed higher free amino acid levels, whereas females showed higher equivalent umami concentrations at selected stages. Gas chromatography-ion mobility spectrometry revealed sex-dependent volatile organic compound (VOC) profiles. Aldehydes were enriched in females after 90 days, whereas males retained more pronounced ketone- and ester-related characteristics. Fourteen key discriminative VOCs were selected. Correlation analysis linked changes in VOC profiles with nucleotide degradation, amino acid changes, fatty acid composition, and lipid oxidation; notably, 1-penten-3-one was positively correlated with malondialdehyde and negatively correlated with eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and arachidonic acid (ARA). These associations provide new insights into sex-specific changes in flavor-related chemical profiles during frozen storage and provide a scientific basis for improving quality evaluation and frozen-storage strategies for mussels in the seafood industry.