Process wash water and washed products from three different fresh produce processing lines were characterized at commercial scale. Different physicochemical and microbiological characteristics of wash water were measured. Great variability between processing lines on the physicochemical quality of process wash water was observed, caused in part by the type of produce washed. The relationship between lower aerobic mesophilic bacteria and higher free chlorine (FC) concentrations in wash water was detected (Pearson's correlation coefficient (PCC) = −0.53). Independently of the FC concentration, most of the water samples (>80%) showed presence of cultivable (limit of detection 1 CFU/100 mL), probably caused by the uncontrolled pH conditions. Higher values of FC and oxidation-reduction potential (ORP) in wash water were related to lower microbial load in washed produce (PCC = −0.82, and − 0.79, respectively). Higher concentration of chlorine was linked to a higher presence of disinfection by-products (DBPs) in the wash water, and washing in chlorinated water led to a significant increase in the concentration of DBPs in produce. However, the accumulation of trihalomethanes (THMs) in process wash water was not correlated with higher concentrations of these DBPs in produce.

Industrial relevance

The washing step of fresh produce processing lines is a critical process. The dose of disinfectants needs to be adequately optimized to avoid microbial contamination without generating the accumulation of disinfection by-products (DBPs). In this study, critical parameters that influence the efficacy of water disinfection and the occurrence of DBPs in fresh produce processing lines were identified under commercial conditions. The results evidenced that monitoring and control of pH play a critical role by maximizing the concentration of the most active form of chlorine in the water. The parameter UV254 measured on-line in the washing tank, can be suggested as a suitable indicator of the presence of organic matter in fresh produce wash water.

中文翻译：

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新鲜农产品商业洗涤生产线的微生物和化学特性突显了对过程水控制的需求

以商业规模对来自三个不同的新鲜农产品生产线的工艺洗涤水和洗涤产品进行了表征。测量了洗涤水的不同理化和微生物特性。观察到各生产线之间对洗涤用水的物理化学质量的巨大差异，部分原因是洗涤产物的类型。检测到较低的需氧嗜温细菌与洗涤水中较高的游离氯（FC）浓度之间的关系（Pearson相关系数（PCC）= -0.53）。与FC浓度无关，大多数水样品（> 80％）显示出可培养的土壤（检测极限为1 CFU / 100 mL），这可能是由于不受控制的pH条件引起的。洗涤水中较高的FC和氧化还原电位（ORP）值与洗涤产品中较低的微生物负荷有关（PCC分别为-0.82和-0.79）。较高的氯浓度与洗涤水中消毒副产物（DBPs）的较高存在有关，在氯化水中洗涤导致农产品中DBPs浓度的显着增加。但是，过程洗涤水中三卤甲烷（THMs）的积累与产品中这些DBP的较高浓度无关。

行业相关性

新鲜农产品生产线的洗涤步骤是关键过程。消毒剂的剂量需要充分优化，以避免微生物污染而不产生消毒副产物（DBP）的积累。在这项研究中，确定了在商业条件下影响水消毒效率和新鲜农产品加工生产线中DBPs发生的关键参数。结果表明，pH值的监测和控制通过最大化水中最活跃形式的氯的浓度起着至关重要的作用。可以建议在洗涤罐中在线测量的参数UV254可作为新鲜农产品洗涤水中有机物存在的合适指标。