Silver Nanoparticle Incorporated Flaxseed Protein-Alginate Composite Films: Effect on Physicochemical, Mechanical, and Thermal Properties

Abstract

In the present study, flaxseed protein-alginate films were prepared with different concentrations of silver nanoparticles (AgNPs) and were evaluated for the physicochemical, mechanical, barrier, and thermal properties. The presence of AgNPs in the protein-alginate films significantly affected the properties of films. Film thickness and moisture content increased proportionally with an increase in the concentration of AgNPs; however, the solubility was decreased. A decrease in L* value and an increase in a* and b* values, along with an increase in total color change was observed with the addition of AgNPs. The mechanical properties of films were improved with the addition of AgNPs, as indicated by the results of tensile strength and percentage elongation. Water vapor permeability was reduced, which showed the improvement in barrier properties of films. Differential scanning calorimetry and thermal gravimetric analysis results indicated improvement in the thermal stability of AgNPs incorporated flaxseed-alginate films. The study on the influence of AgNPs on bacterial inactivation showed that, compared to the control film, all films integrated with silver nanoparticles had strong antibacterial action. The inhibition zones obtained at various AgNP concentrations revealed that the antibacterial activity of AgNPs against Gram-negative (E. coli) bacteria was greater than that of Gram-positive (S. aureus) bacteria. Therefore, silver nanoparticles incorporated flaxseed protein-alginate films have the potential to be used as an antimicrobial food packaging film.