Effect of CuS reinforcement on the mechanical, water vapor barrier, UV-light barrier, and antibacterial properties of alginate-based composite films.

Alginate-based functional nanocomposite films were prepared by the incorporation of copper sulfide nanoparticles (CuSNP) using a solution casting method and characterized their properties. The optical, mechanical, water vapor barrier, surface wetting, and thermal stability properties of the nanocomposite films were tested. The antibacterial activity of the alginate/CuSNP composite film was evaluated against foodborne pathogenic bacteria, E. coli and L. monocytogenes. The morphological test showed that the CuSNP were evenly distributed in the alginate matrix. The addition of 0.5 wt% of CuSNP improved the UV-barrier, hydrophobicity, mechanical strength, and water vapor barrier properties of the alginate-based film; however, the thermal stability was not significantly influenced. The alginate/CuSNP nanocomposite film showed evident antibacterial activity against the Gram-negative (E. coli) bacteria, but only slightly slowed the growth rate of the Garm-positive (L. monocytogenes) bacteria. The alginate/CuSNP nanocomposite films with significantly improved physical and functional properties have a high potential for active food packaging applications.