Antimicrobial Effects of Selenium and Chitosan Nanoparticles on Raw Milk and Kareish Cheese

The contamination of milk and its dairy products with different microorganisms could cause public health hazards. Antibacterial nanoparticles (NPs) are a novel way to ensure that milk and milk products are safe. The present study investigated the effect of chitosan NPs (CS-NPs) and selenium NPs (Se-NPs) on some microorganisms, which consequently affect raw milk and Kareish cheese. Small-sized nanomaterials of Se-NPs and CS-NPs at the size of approximately 20 nm were used in this study. The samples were 700 ml raw milk and 700g Kareish cheese manufactured from 3000 mg milk. The concentrations of used nanoparticles were 0.5%, 1%, and 1.5% for Se-NPs and 2.5%, 5%, and 10% for CS-NPs. They were used to improve the microbial properties of milk and Kareish cheese samples during storage at the refrigerated temperature of 4°C. The aerobic plate count, Enterobacteriaceae count, Staphylococcus count, and mold count were significantly reduced in milk and Kareish cheese samples treated with CS-NPs and Se-NPs. The study has confirmed that CS-NPs and Se-NPs indicated high antimicrobial activity against the studied microorganisms at all concentrations although CS-NPs were more effective than Se-NPs. It can be concluded that these NPs can be used as preservatives in milk and milk products, such as Kareish cheese. In addition, increasing the concentrations of these NPs by 10% for CS-NPS and 1.5% for Se-NPS boosted their effects.