Crook Jennifer A, Rossitto Paul V, Parko Jared, Koutchma Tatiana, Cullor James S
1 Veterinary Medicine Teaching and Research Center, School of Veterinary Medicine, University of California , Davis, Tulare, California.
2 Agriculture and Agri-Food Canada, Guelph Food Research Center , Guelph, Ontario, Canada .
Foodborne Pathog Dis. 2015 Jun;12(6):506-13. doi: 10.1089/fpd.2014.1843. Epub 2015 Apr 17.
Nonthermal technologies are being investigated as viable alternatives to, or supplemental utilization, with thermal pasteurization in the food-processing industry. In this study, the effect of ultraviolet (UV)-C light on the inactivation of seven milkborne pathogens (Listeria monocytogenes, Serratia marcescens, Salmonella Senftenberg, Yersinia enterocolitica, Aeromonas hydrophila, Escherichia coli, and Staphylococcus aureus) was evaluated. The pathogens were suspended in ultra-high-temperature whole milk and treated at UV doses between 0 and 5000 J/L at a flow rate of 4300 L/h in a thin-film turbulent flow-through pilot system. Of the seven milkborne pathogens tested, L. monocytogenes was the most UV resistant, requiring 2000 J/L of UV-C exposure to reach a 5-log reduction. The most sensitive bacterium was S. aureus, requiring only 1450 J/L to reach a 5-log reduction. This study demonstrated that the survival curves were nonlinear. Sigmoidal inactivation curves were observed for all tested bacterial strains. Nonlinear modeling of the inactivation data was a better fit than the traditional log-linear approach. Results obtained from this study indicate that UV illumination has the potential to be used as a nonthermal method to reduce microorganism populations in milk.
非热技术正在作为食品加工业中热巴氏杀菌的可行替代方法或补充利用方法进行研究。在本研究中，评估了紫外线（UV）-C光对七种牛奶传播病原体（单核细胞增生李斯特菌、粘质沙雷氏菌、森夫滕贝格沙门氏菌、小肠结肠炎耶尔森菌、嗜水气单胞菌、大肠杆菌和金黄色葡萄球菌）的灭活效果。将病原体悬浮在超高温全脂牛奶中，在薄膜湍流通过式中试系统中以4300 L/h的流速在0至5000 J/L的紫外线剂量下进行处理。在所测试的七种牛奶传播病原体中，单核细胞增生李斯特菌对紫外线的抵抗力最强，需要2000 J/L的UV-C照射才能达到5个对数级的减少。最敏感的细菌是金黄色葡萄球菌，仅需1450 J/L就能达到5个对数级的减少。本研究表明，存活曲线是非线性的。所有测试菌株均观察到S形灭活曲线。灭活数据的非线性建模比传统的对数线性方法更合适。本研究获得的结果表明，紫外线照射有潜力作为一种非热方法来减少牛奶中的微生物数量。
