Antimicrobial Effect of Biopolymer Packaging Materials with Silver Nanoparticles for Food Storage

Food quality and safety issues are among the most pressing and important for manufacturers, retailers, and end consumers. However, the development of pathogenic microorganisms in such products not only reduces their shelf life but also causes the development of infectious diseases in consumers. Therefore, there is currently an urgent need to find new packaging materials with antimicrobial effects that are non-toxic to humans, food, and the environment. The aim of this article is to study the antimicrobial activity of silver-containing nanocomposites formed based on polylactide (PLA) and polycaprolactone (PCL) with silver nanoparticles by sputtering deposition. Methods. The structure of silver-containing nanocomposites were investigated by the method of wide-angle X-ray diffraction on an XRD-7000 diffractometer. The morphology of Ag nanoparticles on the surface of the films was studied by transmission electron microscopy method. The antimicrobial activity of silver-containing nanocomposites was determined by agar diffusion assays against opportunistic pathogens S. aureus, E. coli, P. aeruginosa, and C. albicans. The study of the impact of packaging biopolymer materials with silver nanoparticles on the total number of mesophilic aerobic and facultatively anaerobic microorganisms, bacteria of the Escherichia coli group, mold and yeasts in food products, were studied by DSTU for 30 days. Results. The presence of metallic silver on the PLA-PCL film surface was confirmed by wide-angle X-ray diffraction. This is indicated by the presence of two low-intensity maxima at 2θm ~ 380 and 440 in the diffractograms of the samples. These maxima correspond to the crystallographic planes of the face-centered cubic lattice of silver, are characterized by indices (111) and (200), respectively, and confirm the presence of metallic silver on the surface of the polylactide-polycaprolactone film. The analysis of the micrographs of the nanocomposites showed that when silver nanoparticles were sputtered on the surface of the PLA-PCL polymer matrix, a layer with a thickness of about 425 nm was formed. It was found that the prepared biopolymer packaging materials PLA and PLA-PCL with Ag nanoparticles sputtered for 3 and 5 min showed antimicrobial activity against S. aureus and E. coli and were inactive against B. subtilis and P. aeruginosa. Packaging bakery products in biopolymer films helps reduce the loss of crumb moisture during storage, slows down the loss of hydrophilic properties, and reduces fragility, which helps extend the shelf life of fresh bread. The moisture content in packaged pumpkin seeds remained stable for two months at the control level. It was found that in wheat bread (for 7 days) and pumpkin seeds (for 30 days), packaged using all types of packaging material PLA-PCL, PLA-PCL-Ag, and conventional PA/PE vacuum film throughout the experiment, no quantitative changes in MAFAnM microorganisms, yeasts, and molds were observed. Studies of the antimicrobial effect of the biopolymer packaging material PLA-PCL-Ag have demonstrated the quality and safety of the films produced, as the calculated values of the total number of microorganisms, yeast and molds, in particular, meet the standards of DSTU. Conclusions. The data obtained suggest that the formed biopolymer packaging materials have antimicrobial properties and are promising for use in the food industry for food packaging, which can extend the shelf life of various product groups without alteration in quality and safety indicators.