MICROBIOLOGICAL AND PHYSICOCHEMICAL EVALUATION OF CHITOSAN NANOPARTICLES OF CHEMICAL AND FOOD GRADE, LOADED WITH LIQUID SMOKE AND THEIR APPLICATION IN TROUT FILLETS (Oncorhynchus mykiss)

Tuesta-Chavez T.; Salazar C.; Silva M.I.; Alarcon H.; Valderrama A.C. · African Journal of Food, Agriculture, Nutrition and Development (2026) · DOI: 10.18697/ajfand.148.26380

Resumen

The growing demand for natural and safe preservatives has increased interest in biopolymer-based delivery systems capable of enhancing the stability and activity of natural antimicrobials. This study evaluated food-grade chitosan (QGA) and chemical-grade chitosan (QGQ) nanoparticles (NPs) as carriers for liquid smoke (LS), with a focus on their potential use in extending the shelf life of rainbow trout fillets (Oncorhynchus mykiss). The objective was to determine whether QGA nanoparticles offer a safer and more effective option for food applications. Nanoparticles were prepared using ionic gelation and characterized by dynamic light scattering (DLS), polydispersity index (PDI), zeta potential, and scanning electron microscopy (SEM). The LS encapsulation efficiency averaged 68.3% with particle sizes ranging from 178 to 423 nm, PDI values between 0.23 - 0.34, and both formulations showed zeta potentials above +40 mV, confirming good colloidal stability. Both nanoparticle types exhibited high antioxidant activity (~95%) and strong antimicrobial effects, achieving roughly 90% inhibition against Gram-positive and Gram-negative bacteria. Minimum inhibitory concentrations were 12.5% for Gram-positive and 50% for Gram-negative strains. Microbiological tests on trout fillets treated with the nanoparticles showed marked preservative effects, suppressing the growth of mesophilic aerobic bacteria, lactic acid bacteria, Escherichia coli, Staphylococcus aureus, and Salmonella spp. Fillets treated with QGA-LS and QGA nanoparticles consistently showed better stability than those treated with QGQ, indicating that food-grade chitosan provides a more suitable matrix for LS encapsulation. Overall, the results demonstrate that food-grade chitosan nanoparticles are effective carriers for liquid smoke, combining high encapsulation efficiency, strong bioactivity, and significant improvements in the microbial stability of perishable foods. This work supports the development of natural, chitosan-based preservative systems for the food industry.

Instituciones: Universidad Nacional Agraria La Molina; Universidad Nacional de Ingeniería