Intelligent films of marine polysaccharides and purple cauliflower extract for food packaging and spoilage monitoring

In this study, metalloanthocyanin-inspired, biodegradable packaging films were developed by incorporating purple cauliflower extracted (PCE) anthocyanins into alginate (AL)/carboxymethyl chitosan (CCS) hybrid polymer matrices based on complexation of metal ions with these marine polysaccharides and anthocyanins. PCE anthocyanins-incorporated AL/CCS films were further modified with fucoidan (FD) because this sulfated polysaccharide can form strong interactions with anthocyanins. Metals-involved complexation (Ca2+ and Zn2+-crosslinked films) improved the mechanical strength and water vapor permeability but reduced the swelling degree of the films. Zn2+-cross-linked films exhibited significantly higher antibacterial activity than did pristine (non-crosslinked) and Ca2+-cross-linked films. The metal ion/polysaccharide-involved complexation with anthocyanin reduced the release rate of anthocyanins, increased the storage stability and antioxidant capability, and improved the sensitivity of the colorimetric response of the indicator films for monitoring the freshness of shrimp. The anthocyanin-metal-polysaccharide complex film showed great potential as active and intelligent packaging of food products. [Display omitted] •Marine polysaccharides-based films containing PC anthocyanins were prepared.•The intelligent films have antioxidant, antimicrobial and pH-sensitive properties•Fucoidan and metal complexation affect the stability and release of anthocyanins•Metal ions-based cross-linking affects film's physical and mechanical properties•Ca2+-cross-linked film has the highest sensitivity in response to seafood spoilage