Coiled tube UV reactors were used to investigate the influence of tube diameter (1.6 mm ID, and 3.2 mm ID) and Reynolds number (Re) to inactivate Escherichia coli W1485 and Bacillus cereus spores in raw soymilk (RSM). Four levels of Re (343, 686, 1029 and 1372) were tested in RSM inoculated separately with each bacterium and treated in the UV reactors at a constant residence time of 11.3 s with UV-C dose of 11.187 mJ/cm 2 at 253.7 nm. Inactivation efficiency of both microorganisms increased with Re. Maximum reductions of 5.6 log10 CFU/ml of E. coli and 3.29 log10 CFU/ml of B. cereus spores were achieved in the 1.6 mm ID UV reactor. Inactivation efficiency was higher in the 1.6 mm ID UV reactor than the 3.2 mm ID UV reactor for both the organisms. Effect of UV-C light on lipid oxidation of untreated RSM, measured as malondialdehyde and other reactive substances (MORS) content, was much higher (95 nmol/ml) than the UV-treated (58 nmol/ml) and thermally pasteurized (55 nmol/ml) RSM during the storage period of 7 days. The UV-C treatment can be effectively used for reducing E. coli cells and B. cereus spores in soymilk without compromising its quality.

This article reviews the status and scope of ultraviolet (UV) light technology in food processing industry for control of foodborne pathogens and spoilage organisms for food safety and shelf life extension. The literature suggests that there have been extensive studies on application of ultraviolet light for disinfection of apple ciders. FDA acceptable reduction of pathogens and spoilage organisms were reported by UV treatment of for apple cider. Several recent studies on UV treatment of milk suggest that there is more work needed to improve design of UV reactors for raw milk processing. Fresh produce industry will also benefit from UV processing so that occurrence of frequent outbreaks can be avoided. A brief review of recent applications in produce industry has also been reported. Finally a recommendation was made for future direction of UV application research in food processing industry.

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