Inactivation of milk-borne pathogens by blue light exposure

Food safety arid quality management play a pivotal role in the dairy industry. Milk is a highly nutritious food that also provides an excellent medium for growth of pathogenic microorganisms. Thus, dairy industry focuses most of their processes arid costs on keeping contamination levels as low as possible. Thermal processes for microbial decontamination may be effective; however, they cannot provide excellent organoleptic, nutritional, arid decontamination properties simultaneously. In this scenario, microbial inactivation by exposure to blue light is a promising alternative method in the food industry due to its intrinsic antimicrobial properties free of any thermal effect. Therefore, this study aimed to determine the inactivation kinetics induced by blue light (lambda = 413 nm) against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella Typhimurium, and Mycobacterium fortuitum cells suspended in whole milk or saline solution. We also performed a series of optic spectroscopies to investigate possible degradation of milk components. All species were sensitive to photoinactivation suspended either in saline solution or milk. Inactivation kinetics differs significantly depending on the suspension medium and each species is differently affected. All bacterial species tested presented more than 5 log in of inactivation within less than 2 h of irradiation (720 J/cm(2)). Infrared spectroscopy did not reveal any significant alteration in any of the milk constituents (e.g., sugars, proteins, arid lipids). Riboflavin vitamin B-2) was the only significantly degraded constituent found. Therefore, we conclude that microbial inactivation performed by blue light presents extraordinary potential for processes in the dairy industry.