A Confirmation with the Limited Difference of Vacuum Impregnated Chitosan Coatings with Different Molecular Weights on Quality Retention of Refrigerated Carp Fillets

The preservation performance of vacuum impregnated chitosan coatings with different molecular weights (Mw; LC 50 kDa; MC 200 kDa; HC 500 kDa) for refrigerated grass carp fillets were evaluated. LC initially had higher activity against lipid oxidation and bacteria as evidenced by the lowest values of TBARS and TVC among groups on day 1. As storage time increased, the advantages of MC and HC on the quality retention for fillets were gradually manifested, with relatively better indicator parameters being recorded when compared to LC. Compared to Control, three coatings were all conducive to retarding quality degradation of fillets in terms of sensory evaluation, microbial enumeration and physicochemical analysis, but the similar performance was also observed among coatings with no significant difference at multiple sampling points. Accordingly, the finding suggested to some extent Mw was not a critical factor for subsequent optimization of chitosan-based coating preservation for fresh fish flesh.