The residual free chlorine level in fresh produce wash solution is closely correlated to the chemical and microbial safety of produce. Excess amount of free chlorine can quickly react with organic matters to form hazardous disinfection by-products (DBPs) above EPA-permitted levels, whereas deficiency of residual chlorine in produce wash solution may result in incompletely removing pathogens on produce. The purpose of this study was to develop a chlorine dosing strategy to optimize the chlorine dosage during produce washing process without impacting the microbial safety of fresh produce. Prediction equations were developed to estimate free chlorine needed to reach targeted residual chlorine at various sanitizer pH and organic loads, and then validated using fresh-cut iceberg lettuce and whole strawberries in an automated produce washer. Validation results showed that equations successfully predicted the initial chlorine concentration needed to achieve residual chlorine at 10, 30, 60, and 90 mg/L for both lettuce and strawberry washing processes, with the root mean squared error at 4.45 mg/L. The Escherichia coli O157:H7 reductions only slightly increased on iceberg lettuce and strawberries with residual chlorine increasing from 10 to 90 mg/L, indicating that lowering residual chlorine to 10 mg/L would not compromise the antimicrobial efficacy of chlorine-based sanitizer. Based on the prediction equations and E. coli O157:H7 reduction results, a chlorine dosing strategy was developed to help the produce industry to maintain microbial inactivation efficacy without adding excess amount of free chlorine. PRACTICAL APPLICATION The chlorine dosing strategy can be used for fresh produce washing process to enhance the microbial food safety and minimize the DBPs formation potential.

中文翻译：

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制定新鲜农产品清洗过程中的氯剂量策略，以维持微生物食品安全并最大限度地减少残留氯


生鲜农产品清洗液中的残留游离氯水平与农产品的化学和微生物安全密切相关。过量的游离氯会迅速与有机物反应，形成高于 EPA 允许水平的危险消毒副产物 (DBP)，而农产品清洗溶液中残留氯的不足可能会导致农产品上的病原体无法完全去除。本研究的目的是开发一种氯剂量策略，以优化农产品清洗过程中的氯剂量，而不影响新鲜农产品的微生物安全。开发了预测方程来估计在各种消毒剂 pH 值和有机负荷下达到目标余氯所需的游离氯，然后在自动农产品清洗机中使用鲜切卷心生菜和整个草莓进行验证。验证结果表明，方程成功预测了生菜和草莓清洗过程中余氯达到 10、30、60 和 90 mg/L 所需的初始氯浓度，均方根误差为 4.45 mg/L。当余氯从 10 mg/L 增加至 90 mg/L 时，卷心生菜和草莓上的大肠杆菌 O157:H7 减少量仅略有增加，表明将余氯降低至 10 mg/L 不会影响氯基消毒剂的抗菌功效。根据预测方程和大肠杆菌 O157:H7 还原结果，制定了氯剂量策略，以帮助农产品行业在不添加过量游离氯的情况下保持微生物灭活功效。 实际应用 加氯策略可用于生鲜农产品清洗过程，以增强微生物食品安全并最大限度地减少 DBP 形成的可能性。