Arachin amyloid-like fibrils and chitosan composite coatings with antimicrobial and antioxidant activities for effective preservation of perishable fruits.

Abstract

Plant-derived essential oil (EO) and bioactive ingredients are popular in the development of functional packaging. In this study, arachin amyloid-like fibrils (AF) and chitosan (CS) were applied to prepare the protein-polysaccharide complex (AF-CS) and combined with betanin (Bet) to construct supramolecular complex (AF-CS-Bet). Then cinnamon essential oil (CEO) was encapsulated by AF-CS and AF-CS-Bet to form Pickering emulsions (AF-CS-CEO, AF-CS-Bet-CEO). The structure, antioxidant and antimicrobial activities of the complexes and emulsions were investigated and their preservation effect on perishable fruits were evaluated. Results showed that the AF-CS-Bet complex exhibited an intricate network structure and the Pickering emulsions showed excellent physical stability (zeta potential >30 mV). AF-CS-Bet complex and AF-CS-Bet-CEO emulsion showed higher antioxidant activity than AF-CS and AF-CS-CEO, respectively. Meanwhile, the emulsion exhibited improved antimicrobial activities than the complexes. Particularly, AF-CS-Bet-CEO emulsion possessed stronger DPPH•- and ABTS•+ radical scavenging activities (77.16 %, 89.01 %), higher inhibition rate for E. coli (99.34 %), S. aureus (99.62 %) and B. cinerea (99.04 %). During the storage of berries, the strawberries coated with AF-CS-Bet complex maintained a better quality, while the AF-CS-Bet-CEO emulsion coatings exerted better preservation effect on the grapes. Overall, this study may provide a novel approach to design biopolymer-based active packaging.