Development and evaluation of soy protein isolate-based antibacterial nanocomposite films containing cellulose nanocrystals and zinc oxide nanoparticles

This study aimed to develop soy protein isolate (SPI)-based active nanocomposite films reinforced with cellulose nanocrystals (CNC), zinc oxide nanoparticles (ZnONP), CNC/ZnONP mixture (physical mixing), or CNC@ZnONP nanohybrids (in situ growth). The tensile strength, oxygen and water vapor barrier properties, water resistance ability, and thermal stability were substantially improved by the incorporation of nano reinforcements, particularly the CNC-containing agents. However, the nanocomposite films displayed a lower elongation at break, surface hydrophobicity, and transmittance compared with the pure SPI-based film. The filling effect of reinforcements and their hydrogen bonds with the film matrix contributed to the formation of a compact and homogeneous film structure. The ZnO-containing films obviously inhibited the growth of foodborne pathogens (Escherichia coli and Staphylococcus aureus) and also reduced the total viable counts and the total volatile basic nitrogen values in a pork sample. Furthermore, the CNC@ZnONP film prevented the migration of zinc from the film into the food system. Therefore, the obtained nanocomposite films have broad application prospects in the field of active food packaging.