Ultraviolet Disinfection Of Beer

Beer is a kind of bacterial fermentation beverages. Considering the bacterial instability and the drinking safty, most of them is treated by disinfection or sanitation. But now the conventional pasteurization and membrane filtration will destory the beer quality. This research is dedicated to apply the ultraviolet(UV) disinfection technology, a kind of cold pasturization, to beer sanitation. And at the base of keeping the beer flavor and quality, the treated druft beer's microorganizms can be less than the stardands, and its shell life can be prolonged.First, the smell, taste and flavor were not significantly influenced by the UV treatment verified by numerous sensory tests with statistically significant level of 5%. In other words, the UV rays cannot ruin the beer's flavors nearly, so we can conduct the disinfection experiments.Second, we developed a novel nonthermal UV apparatus to sterilize beer, which consisted of a UV light (UV-C) source system and an optical-fiber thin film photoreactor. The experiments to sterilize E.col(ATCC 25922),Bacilius subtilis(ATCC 9372) and Saccharomyces cerevisiae (AS 2.4) optimized that two high UV intensity units(15 fibers/cm2) are in series, and the optimal film thicknesses is 3.0mm for Kingway2008 beer. And their inactivation rates at beer flow rate of 3L/h were greater than 99.2%,99.9% and only 94%, respectively. However, a little of S. cerevisiae in beer is beneficial for tast. Moreover, the optimal film thicknesses for Kingway draft beer is 2.5mm. Contaminating lactic acid bacteria and Enterobacteriaceae in the draft beers could be effectively inactivated to achieve the GB2758-2005 stardands.Third, we completed two experiments to decide the influence of UV to beer. On one hand, we used GC to determin esters increased a few and no significant substance's change in beer after UV radiation. On the other hand the shelf life of fresh draft beer could be evidently extended from 7 days to 20 days, at 4℃; 2 days to 7 days, at 25℃.we can obtain that UV traeatment to beer can enhance the floavors, decrease alcohol, inacativate spoilage bacteria, inprove the bacterial instability, and extend the shelf life. This can not only provide a theory comprehensin of liquid food disinfection, but also have great realitic significance to consumers and beer factories.