The potential of using ultraviolet light (UV) in combination of peracetic acid (PAA) as an alternative to chlorine washing for lettuce was evaluated. Shredded iceberg lettuce was dip-inoculated with a four-strain Salmonella cocktail to final levels of 6-7.5 log CFU/g, following by air-drying and overnight cold storage. The inoculated lettuce (80 g) was then washed in turbid tap water containing 6% lettuce juice extract and silicon dioxide (turbidity of ~60 NTU; COD of ~2000 mg/L) while being treated with 1) 10 or 20 ppm free chlorine, 2) PAA solution (40 and 80 ppm), 3) UV (10, 20 and 30 mW/cm2), 4) a combination of UV and PAA for 1, 2, and 5 min. Among all the single treatments, the 30 mW/cm2 UV treatment achieved the highest Salmonella reduction on lettuce. For the 2-min treatment group, the 30 mW/cm2 UV treatment achieved 1.98 log reduction, while the 80 ppm PAA and 20 ppm free chlorine resulted in 1.52 and 1.23 log reduction, respectively. The combined treatment of 30 mW/cm2 UV and 80 ppm PAA achieved significantly higher (P < .05) Salmonella reduction than the 20 ppm free chlorine washing. For the 5-min treatment group, the combined treatment resulted in 3.24 log reduction, while the 20 ppm free chlorine washing only achieved 1.24 log reduction. The effect of the combined treatment of 30 mW/cm2 UV and 80 ppm PAA was also compared with 20 ppm free chlorine washing on larger sample sizes of 200, 500, and 1000 g lettuce. The increase of sample size from 80 g to 1000 g did not significantly (P < .05) affect the inactivation of Salmonella on lettuce for the combined treatment. In addition, the combined treatment of 80 ppm PAA and 30 mW/cm2 UV was able to maintain the Salmonella population in wash water under the detection limit of 0.3 log CFU/mL. It was therefore concluded that the combined treatment of 30 mW/cm2 UV and 80 ppm PAA could be used as an alternative to chlorine washing for lettuce decontamination.

中文翻译：

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评估紫外线和过氧乙酸联合处理替代氯洗的生菜去污效果。


评估了使用紫外线 (UV) 与过乙酸 (PAA) 组合作为生菜氯洗替代品的潜力。将切碎的卷心生菜用四株沙门氏菌混合物浸接至最终水平 6-7.5 log CFU/g，然后风干并冷藏过夜。然后将接种的生菜 (80 g) 在含有 6% 生菜汁提取物和二氧化硅的浑浊自来水中清洗（浊度约为 60 NTU；COD 约为 2000 mg/L），同时用 1) 10 或 20 ppm 游离氯处理, 2) PAA 溶液（40 和 80 ppm），3) 紫外线（10、20 和 30 mW/cm2），4) 紫外线和 PAA 组合 1、2 和 5 分钟。在所有单一处理中，30 mW/cm2 紫外线处理对生菜的沙门氏菌减少效果最高。对于 2 分钟处理组，30 mW/cm2 紫外线处理实现了 1.98 log 减少，而 80 ppm PAA 和 20 ppm 游离氯分别实现了 1.52 和 1.23 log 减少。 30 mW/cm2 UV 和 80 ppm PAA 的联合处理比 20 ppm 游离氯洗涤的沙门氏菌减少量显着更高 (P < .05)。对于 5 分钟处理组，联合处理导致 3.24 log 减少，而 20 ppm 游离氯洗涤仅实现 1.24 log 减少。还比较了 30 mW/cm2 UV 和 80 ppm PAA 联合处理的效果与 20 ppm 无氯洗涤对 200、500 和 1000 g 生菜的较大样品量的影响。样品量从 80 g 增加到 1000 g 并没有显着 (P < .05) 影响联合处理对生菜上沙门氏菌的灭活。此外，80 ppm PAA 和 30 mW/cm2 UV 的联合处理能够将洗涤水中的沙门氏菌种群维持在 0.3 log CFU/mL 的检测限以下。 因此得出的结论是，30 mW/cm2 紫外线和 80 ppm PAA 的联合处理可以作为生菜去污氯洗的替代方案。