Preservative effects of gelatin encapsulated cinnamaldehyde nano-emulsion on refrigerated grass carp flesh: Specific inhibition of proteolytic bacteria and enhanced quality maintenance during late storage period.

This study developed a gelatin-encapsulated cinnamaldehyde nano-emulsion (GCN), assessed its antibacterial activity against proteolytic bacteria, and explored its preserving effects on microbial, biochemical, and sensory quality of refrigerated grass carp. In bacteria-inoculated flesh models, GCN decreased the relative abundance of proteolytic Shewanella putrefaciens and exhibited a responsive demulsification behavior specifically in the presence of S. putrefaciens. In refrigerated grass carp flesh, GCN more efficiently suppressed the growth of total viable counts, retarded the increase of TCA-soluble peptides, TVB-N, and biogenic amines, and maintained better sensory attributes than a conventional Tween emulsion, especially during the late storage period. Moreover, GCN effectively inhibited proteolytic Pseudomonas fragi and Pseudomonas psychrophila in refrigerated grass carp and decreased their relative abundance. In conclusion, GCN demonstrated an enhanced inhibitory effect specifically on proteolytic bacteria and correspondingly improved preservative effects on grass carp quality, indicating the potential of protein matrices in developing bacteria-responsive delivery systems.