Dual-functional smart konjac glucomannan-based packaging incorporating gelatin-cellulose nanocrystal-stabilized emulsions and synergistic anthocyanin-curcumin dyes

Abstract

To enhance the colorimetric and antibacterial performance of polysaccharide-based packaging, a novel pigment-emulsion system was innovatively designed by incorporating high-stability Pickering emulsions and mixed natural dyes for freshness preservation and real-time monitoring. Specifically, anthocyanin (Ant) and curcumin (Cur) were incorporated konjac glucomannan (Kgm) matrix to expanded pH response range. Then, optimized gelatin (Gel)-cellulose nanocrystals (CNC) complexes (G-CNC7) (pH = 7) were prepared through pH-induced electrostatic interactions through eco-friendly process. Subsequently, thyme essential oil (TEO) Pickering emulsion (GCTEO) was successfully prepared and added to construct high-stability pigment/emulsion film-forming system. The antibacterial and indicative film (Kgm-Ant/Cur-GCTEO) was fabricated. The results showed that GCTEO Pickering emulsion, loaded with TEO, synergized with the inherent functional properties of Ant/Cur, effectively enhanced antibacterial and antioxidant activities. This was verified in the preservation of yellow cherry tomatoes, extending their shelf life quality and freshness. The bactericidal rates of Kgm-Ant/Cur-GCTEO against S. aureus and E. coli reached 97.32 % and 78.36 %, respectively. Furthermore, the pigment-emulsion system improved the stability and rapid responsiveness of the color indicator, expanding its pH response range for effective monitoring of yogurt and seafood freshness throughout various acid-base environments. Moreover, composite films exhibited excellent mechanical properties, light and water vapor/oxygen barrier performance, thermal stability, and enhanced hydrophobicity. This study innovatively developed a stable Pickering emulsion system combined with dual natural pigments, which represents an innovative strategy for preservation and freshness maintenance.