Multifunctional food packaging was prepared by incorporating betalains-rich vegetable amaranth (Amaranthus tricolor L.) extract into quaternary ammonium chitosan (QC)/fish gelatin (FG) blend films. The structures, physical and functional properties of the films with and without amaranth extract (AE) were determined. Results showed betalains-rich AEwas pH-sensitive and could change its colors under alkaline conditions. Structural characterization revealed the interactions between AE and film matrix were based on hydrogen bonds, which influenced the compactness of the films. Notably, AE significantly enhanced the thickness (from 0.076 to 0.089mm), UV-vis light barrier ability, elongation at break (from66.7% to 88.8%), 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (from 6.8% to 95.8% at 5 mg/mL), antimicrobial activity against four foodborne pathogens (Escherichia coli, Staphylococcus aureus, Salmonella typhimuriumand Listeria monocytogenes) and ammonia sensitivity of the films. However, AE remarkably reduced the water vapor permeability (from 34.9 x 10(-11) to 26.4 x 10(-11) g m(-1) s(-1) Pa-1) of the films. Notably, the films containing 5 wt% and 10 wt% of AE were suitable tomonitor the freshness of shrimp. Our results suggested QC/FG filmswith betalains-rich AE could be used as antioxidant, antimicrobial and intelligent packaging in food industry. (C) 2020 Elsevier B.V. All rights reserved.
