Ferric iron accessibility influenced the quality deterioration process of chill-stored grass carp flesh: A combined microbiota and metabolomic study.

This study analyzed the microbiota changes, metabolomic profiles, and quality indices of grass carp flesh added with NaCl, sodium citrate, ferric citrate, and EDTA-2Na to demonstrate the effects of ferric iron accessibility on grass carp spoilage. The results showed that ferric citrate slightly retarded bacterial growth, increased Lactococcus abundance, improved microbiota diversity, and inhibited protein degradation in grass carp flesh. The addition of EDTA-2Na less affected the growth of total viable counts, but promoted the predominance of Pseudomonas, inhibited the degradation of grass carp proteins, and improved quality indices (e.g., TVB-N and putrescine) during storage. Besides, ferric iron accessibility largely influenced bacterial metabolic pathways, such as the stimulation of arginine decarboxylase pathway in samples added with ferric citrate and the upregulation of gluconeogenesis due to EDTA-2Na treatment. These discoveries revealed the effects and mechanisms of ferric iron on fish spoilage and thus provided useful guides for developing new fish preservation strategies.