Future Industries Institute, University of South Australia, Mawson Lakes, South Australia, Australia.
Future Industries Institute, University of South Australia, Mawson Lakes, South Australia, Australia.
Food Microbiol. 2021 Feb;93:103610. doi: 10.1016/j.fm.2020.103610. Epub 2020 Aug 3.
Pre-harvest sanitization of irrigation water has potential for reducing pathogen contamination of fresh produce. We compared the sanitizing effects of irrigation water containing neutral electrolyzed oxidizing water (EOW) or sodium hypochlorite (NaClO) on pre-harvest lettuce and baby spinach leaves artificially contaminated with a mixture of Escherichia coli, Salmonella Enteritidis and Listeria innocua (~1 × 10 colony-forming units/mL each resuspended in water containing 100 mg/L dissolved organic carbon, simulating a splash-back scenario from contaminated soil/manure). The microbial load and leaf quality were assessed over 7 days, and post-harvest shelf life evaluated for 10 days. Irrigation with water containing EOW or NaClO at 50 mg/L free chlorine significantly reduced the inoculated bacterial load by ≥ 1.5 log, whereas tap water irrigation reduced the inoculated bacterial load by an average of 0.5 log, when compared with untreated leaves. There were no visual effects of EOW or tap water irrigation on baby spinach or lettuce leaf surfaces pre- or post-harvest, whereas there were obvious negative effects of NaClO irrigation on leaf appearance for both plants, including severe necrotic zones and yellowing/browning of leaves. Therefore, EOW could serve as a viable alternative to chemical-based sanitizers for pre-harvest disinfection of minimally processed vegetables.
在收获前对灌溉水进行消毒处理可以减少新鲜农产品的病原体污染。我们比较了含有中性电解氧化水（EOW）或次氯酸钠（NaClO）的灌溉水对预先污染有大肠杆菌、肠炎沙门氏菌和无害李斯特菌混合物（每种菌约 1×10 个菌落形成单位/mL，悬浮在含有 100mg/L 溶解有机碳的水中，模拟来自污染土壤/粪便的溅出情景）的生菜和婴儿菠菜叶的消毒效果。在 7 天内评估微生物负荷和叶片质量，并在 10 天内评估收获后的货架期。与未处理的叶片相比，用 50mg/L 游离氯的 EOW 或 NaClO 水灌溉可使接种细菌负荷减少 1.5 个对数级以上，而自来水灌溉则平均减少 0.5 个对数级。EOW 或自来水灌溉对婴儿菠菜或生菜叶片的表面在收获前后都没有明显的视觉影响，而 NaClO 灌溉对两种植物的叶片外观都有明显的负面影响，包括严重的坏死区和叶片发黄/变褐。因此，EOW 可以作为一种可行的替代化学消毒剂，用于对经轻微加工的蔬菜进行收获前的消毒。
