Peroxyacetic acid (PAA) is a commonly used antimicrobial in apple spray bar interventions during post-harvest packing. However, limited information is available about its efficacy against foodborne pathogens on fresh apples under commercial packing conditions. In this study, the practical efficacies of PAA against Listeria monocytogenes on fresh apples during spray bar operation at ambient and elevated temperature were validated in three commercial packing facilities using Enterococcus faecium NRRL B-2354 as a surrogate strain. Apples were inoculated with E. faecium at ~6.5 Log₁₀ CFU/apple and subjected to PAA spray bar interventions per commercial packing line practice. At each temperature and contact time intervention combination, 20–24 inoculated apples were processed together with 72–80 non-inoculated apples. Applying 80 ppm PAA at ambient temperature (17–21 °C) achieved a similar log reduction (P > 0.05) of E. faecium on Granny Smith apples (GSA) in three apple packing facilities, which caused 1.12–1.23 and 1.18–1.32 Log₁₀ CFU/apple reductions of E. faecium on GSA for 30-sec and 60-sec intervention, respectively. Increasing the temperature of the PAA solution to 43–45 °C enhanced its bactericidal effect against E. faecium, causing 1.45, 1.86 and 2.19 Log₁₀ CFU/apple reductions in three packing facilities for a 30-sec contact, and 1.50, 2.24, and 2.29 Log₁₀ CFU/apple reductions for a 60-sec contact, respectively. Similar efficacies (P > 0.05) of PAA at both ambient and elevated temperature were also observed on Fuji apples. Spraying PAA on apples at ambient or elevated temperature reduced the level of E. faecium cross-contamination from inoculated apples to non-inoculated apples but could not eliminate cross-contamination. Data from this study provides valuable technical information and a reference point for the apple industry in controlling L. monocytogenes and verifying the effectiveness of their practices.

过氧乙酸（PAA）是收获后包装期间在苹果喷雾棒干预措施中常用的抗菌剂。但是，关于其在商业包装条件下对鲜苹果中食源性病原体功效的信息尚不多。在这项研究中，在三个商业包装设施中，使用粪肠球菌NRRL B-2354作为替代菌株，验证了PAA对在环境温度和高温下喷杆操作期间新鲜苹果上单核细胞增生性李斯特菌的实际功效。苹果在约6.5 Log ₁₀接种了屎肠球菌 CFU /苹果，并按照商业包装生产线惯例进行了PAA喷淋棒干预。在每种温度和接触时间干预组合下，都处理了20–24个接种苹果和72–80个未接种苹果。在三个苹果包装设施中，在环境温度（17–21°C）下应用80 ppm PAA时，格兰尼·史密斯苹果（GSA）上的屎肠球菌的对数减少量（P  > 0.05）类似，分别为1.12–1.23和1.18–1.32日志₁₀  CFU /苹果削减屎肠球菌上GSA对分别为30秒和60秒的干预。将PAA溶液的温度提高到43–45°C，可以增强其对屎肠球菌的杀菌效果，导致1.45、1.86和2.19 Log ₁₀ 减少了30秒接触的三个包装设备的CFU /苹果减少量，以及减少了60秒接触的1.50、2.24和2.29的₁₀ CFU /苹果减少量。 在富士苹果上，在环境温度和高温下，PAA的功效相似（P > 0.05）。在环境温度或高温下向苹果上喷洒PAA可以减少粪便中大肠杆菌的交叉污染程度，使其从接种的苹果变成未接种的苹果，但不能消除交叉污染。这项研究的数据为控制单核细胞增生李斯特氏菌和验证其实践的有效性提供了有价值的技术信息，并为苹果产业提供了参考。