Plasma activated water (PAW) - gelatin coatings: moderate oxidation of gelatin and controlled release of PAW for preservation of snakehead (Channa argus) fillets

Plasma-activated water (PAW) was utilized to dissolve gelatin for the preparation of antibacterial coatings aimed to preserve snakeheads ( Channa argus ) fillets at 4 °C. PAW significantly enhanced the transparency and viscosity of the gelatin solutions. Specifically, PAW treated for 10 min (PAW 10 ) induced the densest network structure of gelatins with decreased α-helix and increased β-sheet. The antibacterial activity against Escherichia coli and Pseudomonas aeruginosa was enhanced dependently on the preparation time of PAW ( P < 0.05). Furthermore, PAW-gelatin coatings decelerated the release of H 2 O 2 , which favored to reduce the total viable count (TVC) and total volatile base nitrogen (TVB-N) during the storage of fillets ( P < 0.05) and extended the shelf life from 6 days to 9 days. Essentially, G-PAW 10 reduced the crude protease activity of fillets from 102.25 nkat/mL to 7.16 nkat/mL ( P < 0.05), suggesting the suppression in protein degradation and autolysis. Consequently, the muscle fibres of FG-PAW 10 remained intact, smooth and tightly packed, with the shear force increasing from 230.36 g in the control to 839.67 g and the poriness of tissue structures decreasing from 44.97 % to 31.58 % ( P < 0.05), indicating effective structural preservation. • Plasma-activated water (PAW)-gelatin coatings decelerated the release of H 2 O 2 . • PAW improved the transparency and viscosity of the gelatin coatings. • PAW promoted the structural transformation of gelatin from α-helix to β-sheet. • PAW-gelatin coatings inhibited the enzyme activity and autolysis of fish fillets. • PAW-gelatin coatings reduced the TVC and maintained tissue structures of fillets.