Fish gelatin films containing aqueous extracts from phenolic-rich fruit pomace

The aim of the work was to study the feasibility of using aqueous extracts from rowanberry, blue-berried honeysuckle, and chokeberry pomace for the formulation of fish gelatin films with antioxidant and antimicrobial activity as well as improved mechanical and water barrier properties. The predominant phenolic components in rowanberry and chokeberry extracts were hydroxycinnamates, and in blue-berried honeysuckle extract anthocyanins. Although the gelatin film itself showed antioxidative activity, addition of blue-berried honeysuckle extract increased it 3-fold. Unlike the films containing 1.2 mL of extract, the films with increased extract volume possessed strong antimicrobial properties against E. coli, P. fluorescens, S. aureus, L. innocua. Films plasticized with glycerol at 15 and 17.5% did not increase the mechanical strength in the presence of all extracts tested, but at 20%, a positive effect of each extract on mechanical strength was observed. None of the extracts affected the water barrier properties of the films.