Quality enhancement of large yellow croaker treated with edible coatings based on chitosan and lysozyme

Abstract

The aim of this study was to evaluate the preservation effect of chitosan (CS) and lysozyme (Lys) coating on the quality of large yellow croaker (Larimichthys crocea) via physicochemical analyses, microbiological and sensorial assessments during refrigerated storage. Results showed that CS films incorporated with 0.6 mg·mL^-1 of lysozyme exhibited the strongest inhibition effect against S. aureus, whose inhibition zone was 16.10 ± 0.71 mm. The utilization of CS singly, or CS-lysozyme (Lys) coating significantly reduced lipid oxidation (thiobarbituric acid value, TBA) and improved the sensorial scores of fishes. Control and treated groups exceeded the maximum permissible level (30 mg N/100 g) of total volatile basic nitrogen (TVB-N) in fishery products on days 6 (control) and 9 (CS or CS-Lys treated), respectively. Fish samples reached the value of 7.0 Log CFU/g (Total Viable Count, TVC) on days 15 (control), whereas both CS and CS-Lys treated flesh samples never exceed this limit value during the refrigerated storage. Results of our study indicate CS-Lys have high efficiency in inhibiting microorganism growth and lipid oxidation and in maintaining sensorial quality, which is a promising method to maintain the quality and extend the shelf life of refrigerated fishes.

Keywords: Antimicrobial activity; Chitosan; Large yellow croaker; Lysozyme; Preservation effect.