UV-C treatment on the safety of skim milk: Effect on microbial inactivation and cytotoxicity evaluation

The efficacy of UV-C irradiation as a nonthermal processing method for skim milk (SM) was investigated. SM inoculated with two surrogate viruses (MS2 and T1UV), and three bacteria (Escherichia coli ATCC 25922, Salmonella enterica serovar Typhimurium ATCC 13311, and Listeria monocytogenes ATCC 19115) was treated with Deanflow UV-C irradiation, a spiral reactor with the fluid pumped around a central low-pressure mercury UV lamp (40 W) emitting at 254 nm wave-length. A series of known UV doses (0-168.33 mJ center dot cm(2)) were delivered to the samples. The microbial loads of MS2, T1UV, E. coli, Salmonella, and Listeria were reduced by more than 5 log(10). The inactivation kinetics of all microorganisms were best described by log linear models with a low RMSE and higher coefficient of determination (R-2 > 0.95). This study demonstrated that high levels of inactivation of pathogenic particles can be achieved in SM. Practical applications This scientific study provides evidence based data on the advantages of UV-C light in achieving microbial reduction in skim milk. The irradiated skim milk did not show any toxicity on mice liver and intestinal cells. UV-C irradiation is an efficient food preservation technology and offers opportunities for dairy and food processing industries to meet the growing demand from consumers for safer foods. This exploration would provide methodological evidence for commercialization of UV-C processing of milk and dairy based beverages.