Effects of gallic acid combined with epsilon-polylysine hydrochloride incorporated in a pullulan-CMC edible coating on the storage quality of sea bass

The effects of edbile coatings, based on pullulan and sodium carboxymethylcellulose (PUL-CMC) with gallic acid (GA) and/or epsilon-polylysine hydrochloride (PL), on the quality of sea bass (Lateolabrax maculatus) fillets during storage at 4 degrees C for 20 days were assessed in this study. Total viable counts (TVC), thiobarbituric acid (TBA), pH value, total volatile basic nitrogen (TVB-N), water holding capacity (WHC), water migration, texture profiles, and electronic nose results were measured at five day intervals. The results showed that treatments with PUL-CMC-GA, PUL-CMC-PL, and PUL-CMC-GA-PL coatings retarded the increase of the TVC, TBA, pH, and TVB-N value when compared with the results of the control group. These coatings significantly maintained the content of immobile water, WHC, texture and flavor properties of the fish. In addition, use of PUL-CMC-GA-PL was more effective than use of PUL-CMC-GA and PUL-CMC-PL. The TVC, TVB-N, and pH in the PUL-CMC-GA-PL group were all lower than those in the other groups during the whole storage time. The TBA value in the PUL-CMC-GA-PL group remained below 0.7 mg malonaldehyde (MDA) per kg at 20 d, which was extended by 10 d when compared with the values for the other groups. The WHC in PUL-CMC-GA-PL only decreased by 6.53% during 20 d of storage. The results indicated that GA combined with PL had a synergistic effect on improving the preservation properties of PUL-CMC, which could inhibit lipid oxidation, protein degradation and microbial growth, and maintain better texture characteristics during the storage of sea bass fillets.