Krishnamurthy K, Demirci A, Irudayaraj J M
Dept. of Food and Animal Sciences, Alabama A&M Univ., Normal, AL 35762, USA.
J Food Sci. 2007 Sep;72(7):M233-9. doi: 10.1111/j.1750-3841.2007.00438.x.
This study investigated the efficacy of pulsed UV-light for continuous-flow milk treatment for the inactivation of Staphylococcus aureus, a pathogenic microorganism frequently associated with milk safety concerns. Pulsed UV light is an emerging technology, which can be used for the inactivation of this pathogen in milk in a relatively short time. Pulsed UV light damages the DNA of the bacteria by forming thymine dimers that lead to bacterial death. The effect of sample distance from the quartz window of the UV-light source, number of passes, and flow rate was investigated. A response surface methodology was used for the design and analysis of experiments. Milk was treated at 5-, 8-, or 11-cm distance from a UV-light strobe at 20, 30, or 40 mL/min flow rate and treated up to 3 times by recirculation of milk to assess the effect of the number of passes on inactivation efficiency. Log10 reductions varied from 0.55- to 7.26-log10 CFU/mL. Complete inactivation was obtained in 2 cases and no growth was observed following an enrichment protocol. Predicted results were in agreement with the experimental data. Overall, this work demonstrates that pulsed UV-light has a potential for inactivation of milk pathogens.
本研究调查了脉冲紫外光对连续流动牛奶进行处理以灭活金黄色葡萄球菌的效果，金黄色葡萄球菌是一种常与牛奶安全问题相关的致病微生物。脉冲紫外光是一种新兴技术，可在相对较短的时间内用于灭活牛奶中的这种病原体。脉冲紫外光通过形成胸腺嘧啶二聚体来破坏细菌的DNA，从而导致细菌死亡。研究了样品与紫外光源石英窗的距离、通过次数和流速的影响。采用响应面法进行实验设计和分析。牛奶在距离紫外闪光灯5厘米、8厘米或11厘米处，以20毫升/分钟、30毫升/分钟或40毫升/分钟的流速进行处理，并通过牛奶再循环处理多达3次，以评估通过次数对灭活效率的影响。对数减少量在0.55至7.26个对数10 CFU/毫升之间变化。在2个案例中实现了完全灭活，经过富集培养后未观察到生长。预测结果与实验数据一致。总体而言，这项工作表明脉冲紫外光在灭活牛奶病原体方面具有潜力。
