School of Food Science and Environmental Health, Technological University Dublin, Ireland.
School of Food Science and Environmental Health, Technological University Dublin, Ireland; School of Chemical Engineering, University of Sydney, Australia.
Food Microbiol. 2019 Dec;84:103226. doi: 10.1016/j.fm.2019.05.010. Epub 2019 May 25.
Atmospheric cold plasma (ACP) is an effective method for microbiological decontamination. This study evaluated an alternative water-based decontamination approach for inactivation of bacterial population from fresh produce and in the wash water generated from fresh produce washing. The study characterised ACP inactivation of attached Listeria innocua and Pseudomonas fluorescens inoculated on lettuce in comparison to chlorine treatment. P. fluorescens was sensitive to ACP treatment and was reduced below detection limit within 3 min of treatment. L. innocua population was reduced by ∼2.4 Log CFU/g after 5 min of treatment; showing similar inactivation efficacy to chlorine treatment. The microbial load in wash water was continuously decreased and was below detection limits after 10 min of ACP treatment. Micro-bubbling along with agitation assisted the bacterial detachment and distribution of reactive species, thus increasing bacterial inactivation efficacy from fresh produce and wash water. A shift in pH of plasma functionalised water was observed along with high concentration of nitrate and ozone with a relative amount of nitrites which increased with plasma exposure time. Further, L. innocua treated at different independent pH conditions showed minimal or no effect of pH on ACP bacterial inactivation efficacy. Aqueous ACP treatment poses a promising alternative for decontamination of fresh produce and the associated wash-waters which could be applied in the food industry to replace continuous chlorine dosing of process waters.
大气压冷等离子体（ACP）是一种有效的微生物消毒方法。本研究评估了一种替代的水基消毒方法，用于从新鲜农产品中灭活细菌种群，以及从新鲜农产品清洗中产生的洗涤水中灭活细菌种群。该研究对附着在生菜上的无害李斯特菌和荧光假单胞菌进行了 ACP 灭活处理，并与氯处理进行了比较。荧光假单胞菌对 ACP 处理敏感，在处理 3 分钟内即可降低至检测限以下。经过 5 分钟的处理，无害李斯特菌的数量减少了约 2.4 Log CFU/g，与氯处理的灭活效果相当。洗涤水中的微生物负荷持续降低，经过 10 分钟的 ACP 处理后，低于检测限。微曝气和搅拌有助于细菌的脱落和活性物质的分布，从而提高了从新鲜农产品和洗涤水中的细菌灭活效果。等离子体功能化水的 pH 值发生了变化，同时还伴随着高浓度的硝酸盐和臭氧，以及随着等离子体暴露时间的增加而增加的相对亚硝酸盐含量。此外，在不同的独立 pH 条件下处理的无害李斯特菌表明，pH 值对 ACP 细菌灭活效果的影响最小或没有影响。水基 ACP 处理为新鲜农产品及其相关洗涤水的消毒提供了一种很有前途的替代方法，可应用于食品工业，以替代过程水的连续氯投加。
