Comparison of the physical and functional properties of starch/polyvinyl alcohol films containing anthocyanins and/or betacyanins.

Anthocyanins and betacyanins are two different types of natural pigments. In this study, active and intelligent packaging were prepared by adding anthocyanins or betacyanins or anthocyanins/betacyanins mixture (in the weight ratios of 3:1, 1:1 and 1:3) into starch/polyvinyl alcohol (PVA) films. The physical and functional properties of developed films were compared. Results showed anthocyanins were more pH-sensitive than betacyanins. However, betacyanins were more beneficial to improve the compactness of the films and had stronger hydrogen bonding interactions with film matrix as compared with anthocyanins. The addition of anthocyanins and/or betacyanins slightly decreased the crystallinity of the films but significantly increased the ultraviolet-visible light barrier, water vapor barrier, antioxidant, antimicrobial, and ammonia-sensitive properties of the films. Moreover, the barrier, antioxidant and antimicrobial properties of the films increased with the increase of betacyanins proportion. Amongst different films, the film containing anthocyanins/betacyanins mixture in the weight ratio of 1:3 presented obvious color changes when the film was utilized to monitor the freshness of pork. Our results suggested betacyanins was more beneficial to enhance the barrier, antioxidant and antimicrobial properties of starch/PVA films. Starch/PVA films simultaneously added with anthocyanins and betacyanins were more suitable to monitor the freshness of pork.