Application of Low Wave-length UV Irradiation to Inactivate Pathogenic Microbes in Highly Opaque Liquid Foods
UV-C irradiation is a novel non-thermal technology that is lethal to most of the pathogenic microbes in liquid foods. This study investigated the ability of UV-C irradiation to inactivate microorganisms including bacteriophage in coconut water, a highly opaque liquid food. UV-C inactivation kinetics of two surrogate viruses (MS2, T1UV) and three pathogenic bacteria ( E. coli ATCC 25922, Salmonella typhimurium ATCC 13311, Listeria monocytogenes ATCC 19115) in peptone and coconut water were investigated. UV-C irradiation was applied using a collimated beam and flow-through UV reactors operating at 253.7 nm wavelength. The optics (absorption and scattering coefficients) of the fluid are accounted for, and dose delivery is verified through bio-dosimetry, ensuring that target levels of disinfection are achieved, and allowing direct comparisons with other UV-C treatment. A series of known UV-C doses (0–40 mJ˙cm-2) were delivered to the samples in collimated beam and (0–30 mJ˙cm -2) for flow-through system, except MS2 where higher doses were delivered. All the three microbial pathogenic organisms were inactivated by more than 5 log10 (p < 0.05) at highest doses of 40 and 30 mJ˙cm -2 using both reactors. The inactivation kinetics were best described by log linear and exponential models with a low root mean squared error (RMSE) and higher coefficient of determination (R2>0.95). Models for predicting log reduction as a function of UV-C irradiation dose were found to be significant (p < 0.05) with low standard error and high coefficients of determination (R2). This study clearly demonstrated that high levels of inactivation of pathogens can be achieved in coconut water, and suggested significant potential for UV-C treatment of other liquid foods. Therefore, UV-C irradiation could be used as a potential alternative to traditional thermal pasteurization for control of E. coli, L. monocytogenes and S. typhimurium populations to help ensure the safety of fresh coconut water. Further research is suggested to study the organoleptic and nutritional quality of the treated food samples to evaluate the consumer acceptance of the UV treated foods.
Manreet Singh Bhullar,
"Application of Low Wave-length UV Irradiation to Inactivate Pathogenic Microbes in Highly Opaque Liquid Foods"
ETD Collection for Tennessee State University.