Nanoparticle and dialdehyde polysaccharide synergistically improving the physicochemical properties of soy protein isolate films enriched with lingonberry extract

The combination of proteins and anthocyanins showed great potential in constructing smart films, but their weak interactions led to poor mechanical properties in the resulted films. This study enhanced the physicochemical properties of lingonberry extract (LE)-enriched soy protein isolate (SPI) smart active films by incorporating dialdehyde konjac glucomannan (DKGM) as a cross-linker and quercetin-loaded shellac nanoparticles (SNPs-Qu) as fillers. The films' chemical structure, thermal properties, surface and cross-sectional morphology were analyzed using FT-IR, DSC, and SEM, respectively. Additionally, the light-shielding properties, mechanical properties, water vapor permeability, and antioxidant properties of the films were systematically studied. The results indicated considerable interactions among film components. The combination of DKGM with SNPs-Qu significantly enhanced UV absorption while reducing moisture content from 35.07% to 24.84% and water vapor transmission from 0.63 to 0.41 (mm.g.m(-2).h(-1).KPa-1) of the films. Importantly, DKGM positively affected thermal stability and mechanical properties whereas SNPs-Qu improved internal structure and the antioxidant properties of the films significantly. Notably, film color shifted from red to yellow-green with rising pH levels effectively tracking pork filling freshness status. Overall, the smart active film constructed from SPI, LE, DKGM, and SNPs-Qu exhibited excellent physicochemical properties alongside pH-sensitive qualities-promising applications in smart food packaging.