Burnett Autumn R, Critzer Faith, Coolong Timothy
Department of Horticulture, University of Georgia, 1111 Miller Plant Sciences, Athens, GA 30602, USA.
Department of Food Science and Technology, University of Georgia, 100 Cedar Street, Athens, GA 30602-2610, USA.
J Food Prot. 2025 Feb 26;88(3):100458. doi: 10.1016/j.jfp.2025.100458. Epub 2025 Jan 28.
In the United States, the Food and Drug Administration (USFDA) prohibits the distribution of fruit that is dropped from the plant and contacts the ground during harvest. This includes fruit which contacts the ground while attached to the plant, called "drooping" fruit. In the Southeastern US, tomato and pepper are trellised and grown on plastic mulch. The objective of this study was to obtain bacterial transfer rates from a nonpathogenic Escherichia coli GFP inoculated on plastic mulch (black and white) to fruit (tomatoes and peppers) that contact the ground by being dropped (at heights of 30, 60, or 120 cm) or by drooping (contact times of 1 h or 24 h) in the field during the summer season in Georgia, USA. Plastic mulch was surface inoculated with E. coli (10 CFU/64 cm), and after drying, populations were reduced by >2-3 log CFU/64 cm. Once inoculum was dry, the fruit was either dropped from different heights through a PVC pipe or placed back onto the mulch in its initial resting place. The mean log percent transfer of E. coli from plastic mulch to dropped tomato and pepper fruit was -2.00 to 0.46 (0.01-2.88%). Mean log percent transfer rates of E. coli to drooping fruit were between -0.83 and 0.01 (0.15-1.02%), with no significant differences in transfer within crop types between treatments of plastic mulch color or contact time. Field environmental conditions throughout the experiment such as ambient air temperature, relative humidity, UV radiation intensity, and surface temperature of plastic likely affected the rates of bacterial transfer. While other studies have evaluated bacterial survival and transfer from mulch to fruit in a laboratory setting, the present study addresses knowledge gaps in bacterial transfer during drooping and dropping incidents in the field when fruit contacts plastic mulch, providing results that have potential to inform future regulatory guidance for produce harvest and handling.
在美国，食品药品监督管理局（USFDA）禁止分发在收获期间从植株上掉落并接触地面的水果。这包括在仍与植株相连时接触地面的水果，即所谓的“下垂”水果。在美国东南部，番茄和辣椒采用搭架栽培，并种植在塑料薄膜上。本研究的目的是获取接种在塑料薄膜（黑色和白色）上的非致病性大肠杆菌绿色荧光蛋白（GFP）转移到水果（番茄和辣椒）上的细菌转移率，这些水果在夏季于美国佐治亚州的田间通过掉落（高度为30、60或120厘米）或下垂（接触时间为1小时或24小时）接触地面。塑料薄膜表面接种大肠杆菌（10 CFU/64平方厘米），干燥后，菌量减少>2 - 3 log CFU/64平方厘米。接种物干燥后，水果要么通过PVC管从不同高度掉落，要么放回其最初在薄膜上的放置位置。大肠杆菌从塑料薄膜转移到掉落的番茄和辣椒果实上的平均对数转移百分比为-2.00至0.46（0.01 - 2.88%）。大肠杆菌转移到下垂果实上的平均对数转移率在-0.83至0.01之间（0.15 - 1.02%），在塑料薄膜颜色或接触时间处理的作物类型内，转移率没有显著差异。整个实验过程中的田间环境条件，如环境空气温度、相对湿度、紫外线辐射强度和塑料薄膜的表面温度，可能影响了细菌转移率。虽然其他研究在实验室环境中评估了细菌在覆盖物上的存活以及从覆盖物到果实的转移，但本研究解决了田间水果接触塑料薄膜时下垂和掉落事件期间细菌转移方面的知识空白，提供了可能为未来农产品收获和处理的监管指导提供参考的结果。
