Submitted to: Journal of Food Protection
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/4/2005
Publication Date: 8/15/2005
Citation: Geveke, D.J. 2005. Ultraviolet inactivation of bacteria in apple cider. Journal of Food Protection. 68(8):1739-1742. Interpretive Summary: The Food and Drug Administration has recently approved the use of ultraviolet (UV) light as a means of reducing harmful bacteria in juice products; yet, very few juice producers use this technology which promises to preserve the juice's delicious taste and nutrients. A simple and effective UV pasteurizer was developed that destroyed E. coli bacteria in apple cider without heating it. The level of E. coli was reduced by more than 99.998%, and another type of bacteria, Listeria innocua, was reduced by 99.68%. The UV pasteurizer that was developed in this study is small and portable. Processing studies are recommended to evaluate cost and efficiency of this technology in cider operations.
Technical Abstract: Apple cider, inoculated with bacteria, was processed using an ultraviolet (UV) apparatus that is simple and effective. The apparatus consisted of a low pressure mercury lamp surrounded by a coil of UV transparent tubing. Cider was pumped through the tubing at flow rates of 27 to 83 ml/min. The population of Escherichia coli K12 was reduced by 3.4 plus or minus 0.3 log after being exposed for 19 s at a treatment temperature of 25 C. The population of Listeria innocua, which was found to be more resistant to UV, was reduced by 2.5 plus or minus 0.1 log after being exposed for 58 s. The electrical energy for the process was 34 J/ml and is similar to that for conventional thermal processing. UV processing has the potential to improve the safety and extend the shelf life of apple cider while maintaining more of the fresh-like qualities of the cider compared to thermal processing.