Characterization and evaluation of antioxidant and antimicrobial capacity of prepared liquid smoke-loaded chitosan nanoparticles

The combined application of chitosan (CS) and liquid smoke (LS) leads to the development of a suitable material with synergistic properties and promising potential for use as an efficient preservative for the conservation of food products. The present work investigates the development and characterization of liquid smoke-loaded chitosan nanoparticles (LS-CS/NPs) with the optimization of the preparation conditions using response surface methodology and the analysis of the antioxidant and antibacterial properties of the nanoparticles as well as the controlled release of the liquid smoke. The nanoparticles were prepared by the ionic gelation method and were characterized by DLS, zeta potential, FT-IR, SEM, and EDS. The analysis of antioxidant activity of LS-CS/NPs was performed by the free radicals scavenging method (DPPH and ABTS) while the study of the total phenolic content of the particles was conducted via the application of the Folin-Ciocalteau method with some modifications. The analysis of antimicrobial activity of the LS-CS/NPs was performed using the minimum inhibitory concentration method involving the growth of Gram-positive (S. aureus and B. cereus) and Gram-negative (E. coli and Salmonella spp) bacteria. The analysis of the controlled release of liquid smoke was conducted at 4 °C using the Korsmeyer-Peppas model. The results obtained showed that the nanoparticles prepared using CS and LS in the ratio 1.5: 0.583, respectively (F′2), which had an average size of 205 nm and zeta potential of 45 mV, exhibited good antioxidant (%DPPH: 92.7% and %ABTS: 93%) and antibacterial activities, with an efficient, gradual controlled release of liquid smoke (release rate = 0.042 min⁻¹).