Enhancing Ras Cheese Safety: Antifungal Effects of Nisin and its Nanoparticles Against Aspergillus flavus

Abstract

Background Due to adverse effects of industrial chemicals and their carcinogenicity and toxicity for humans, the debates have increased on using natural preservatives. This study was conducted to investigate the inhibitory effect of pure nisin and nisin nanoparticles (nisin NPs) against Aspergillus flavus which was inoculated in laboratory manufactured Ras cheese. A novel, safe, and natural approach of nanoprecipitation utilizing acetic acid was used to create nisin nanoparticles. The prepared NPs were characterized using zeta-sizer, FTIR and transmission electron microscopy (TEM). Furthermore, an evaluation of nisin NPs' cytotoxicity on Vero cells was conducted. The minimum inhibitory concentrations (MICs) of nisin and its nanoparticles were detected in-vitro against A. flavus isolates using agar well-diffusion method. Results The obtained results showed a strong antifungal activity of nisin NPs (3.125%) against A. flavus strain in comparison with pure nisin. Notably, the count decreased gradually by time from 2×10⁸ at zero time and could not be detected at 7^th week. While the count with pure nisin decreased from 2×10⁸ at zero time and could not be detected at 10^th week where it’s enough time to produce aflatoxins in cheese. Additionally, the sensory parameters of the manufactured Ras cheese inoculated with nisin and nisin NPs were of high overall acceptability (OAA). Conclusions Overall, the results of this study suggested that adding more concentration from nisin nanoparticles during the production of Ras cheese may be a helpful strategy for food preservation against A. flavus in the dairy industry.