Smart packaging films based on locust bean gum, polyvinyl alcohol, the crude extract of Loropetalum chinense var. rubrum petals and its purified fractions.

Abstract

Loropetalum chinense var. rubrum is an ornamental shrub rich in polyphenolic compounds. In this study, polyphenolic compounds were extracted from L. chinense var. rubrum petals (LCP) and further purified on macroporous resin column to afford two fractions. The crude extract of LCP (LCP-CE) and its two purified fractions (LCP-25PF and LCP-50PF) were individually incorporated into locust bean gum/polyvinyl alcohol matrix to develop smart packaging films. The structures, physical and functional properties of the films were compared. Results showed LCP-25PF was mainly composed of anthocyanins, while LCP-50PF was mainly composed of chlorogenic acid and vanillin. LCP-CE, LCP-25PF and LCP-50PF interacted with locust bean gum/polyvinyl alcohol matrix through hydrogen bonds, thereby improving the light and oxygen barrier ability, tensile strength, thermal stability, antioxidant activity and antimicrobial activity of the film. The film containing LCP-25PF showed the lowest water vapor permeability (10.36×10-11gm-1s-1Pa-1) and oxygen permeability (0.42cm3mmm-2day-1atm-1) but the highest tensile strength (29.76MPa), antioxidant activity and antimicrobial activity. In addition, the films containing LCP-CE and LCP-25PF had pH-/ammonia-sensitivity and effectively indicated shrimp freshness at 4°C. Results suggested the film containing LCP-25PF could be used as smart packaging film.