Emulsifier free fish gelatin based films with excellent antioxidative and antibacterial activity: Preparation, characterization and application in coating preservation of fish fillets

The gelatin (GL) based film with high antioxidative and antibacterial activity and emulsifier-free was developed. The tensile strength (TS) and elongation at break (EAB) of gelatin films could be improved by adding TEMPO-oxidized cellulose nanofibers (TCNFs). When the content of epigallocatechin gallate (EGCG) and carvacrol (CAR) reached 20 mg and 500 mg, the EAB of the composite film was 61.25%, which was much higher than that of gelatin film (28.73%). EGCG and CAR could improve UV barrier performance of GL/TCNFs films. GL/TCNFs/20EGCG/500CAR film allowed DPPH· and ABTS+ free radical scavenging rates to reach 92.6% and 90.6%, and the diameters of inhibition zones of E. coli and S. aureus were 22.28 mm and 42.58 mm, which showed that EGCG and CAR had synergistic effects. In the coating preservation of sea bass fillets, it also showed excellent inhibition of bacterial proliferation including Pseudomonas aeruginosa, H2S-producing bacteria as well as yeast and mold. TVB-N and TBA of control group were 15.21 mg/100g and 0.353 mg MDA/kg respectively on day 6, while lower values of 5.41 mg/100g and 0.124 mg MDA/kg respectively were recorded for GL/TCNFs/EGCG/500CAR group at the end of storage. All these results indicated that GL/TCNFs/EGCG/CAR film has potential application in fish preservation and is an environmentally friendly active food packaging system.