The development of sustainable biopolymer-based active packaging materials is essential to replace single-use petroleum-derived plastics and reduce food deterioration. In this study, chitosan-based films incorporating green-synthesized silver microparticles (Ag microparticles) obtained from pecan nutshell extract rich in phenolic compounds were developed as multifunctional materials with antioxidant and antibacterial properties. Films were prepared by the casting method using chitosan solutions at different concentrations (1.5–2.5% w/v), with Ag microparticles incorporated at 0.25% (w/v). The phenolic profile of the extract (gallic acid, catechin, ferulic acid, and ellagic acid), determined by UPLC-DAD, confirmed its role as a reducing and stabilizing agent during Ag microparticle synthesis. All film-forming solutions exhibited non-Newtonian pseudoplastic behavior, and variations in viscosity and consistency were directly reflected in the mechanical behavior of the films. Strong antioxidant activity, mainly governed by single-electron transfer mechanisms, was observed in ABTS, DPPH, and FRAP assays. The films also showed pronounced antibacterial activity, achieving complete inhibition of Listeria monocytogenes. Finally, it is concluded that film mechanical properties are strongly governed by the rheological behavior of the chitosan-based film-forming solutions. The resulting chitosan-Ag microparticle films combine suitable mechanical behavior with antioxidant activity and antibacterial effects against Listeria monocytogenes, suggesting their potential for future application in active food-packaging systems.
Pompa-Ramos et al. (Wed,) studied this question.