Incorporating functional colorants in whey protein isolate-cellulose nanocrystal-blended edible films for pork freshness prediction

In this study, intelligent pH- and ammonia-sensing edible films are designed based on whey protein isolate (WPI)-cellulose nanocrystal-based biopolymers by incorporating different functional colorants (curcumin, phycocyanin, and modified lycopene), alone and paired, to promote food freshness and monitoring efforts. Incorporating the colorants endowed the films were endowed with pH- and ammonia-responsiveness and enhanced UV-blocking, antioxidant, and antibacterial capabilities. Phycocyanin induces WPI unfolding, increasing the accessibility of curcumin; hence, combining curcumin with phycocyanin promotes the sensitivity of films to pH and NH3 compared with those containing a single colorant. In the pork freshness monitoring analysis, the combined-colorants film underwent a noticeable color change as the meat spoiled. Moreover, the meat packaged with the combined film exhibited lower levels of lipid oxidation than those packaged in single- colorant films. These results suggest that curcumin-phycocyanin-containing films have multifunctional potential in intelligent food packaging.