Quantification of Escherichia coli Transfer from Plastic Mulch to Field-grown Tomatoes and Bell Peppers

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...

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Main Authors: Autumn R. Burnett, Faith Critzer, Timothy Coolong
Format: Article
Language:English
Published: Elsevier 2025-02-01
Series:Journal of Food Protection
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Online Access:http://www.sciencedirect.com/science/article/pii/S0362028X25000109
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author Autumn R. Burnett
Faith Critzer
Timothy Coolong
author_facet Autumn R. Burnett
Faith Critzer
Timothy Coolong
author_sort Autumn R. Burnett
collection DOAJ
description 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 (106 CFU/64 cm2), and after drying, populations were reduced by >2–3 log CFU/64 cm2. 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, UVAB 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.
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spelling doaj-art-7cb6d59a3cd14902b807d637a305d4712025-02-07T04:46:49ZengElsevierJournal of Food Protection0362-028X2025-02-01883100458Quantification of Escherichia coli Transfer from Plastic Mulch to Field-grown Tomatoes and Bell PeppersAutumn R. Burnett0Faith Critzer1Timothy Coolong2Department of Horticulture, University of Georgia, 1111 Miller Plant Sciences, Athens, GA 30602, USA; Corresponding author.Department of Food Science and Technology, University of Georgia, 100 Cedar Street, Athens, GA 30602-2610, USADepartment of Horticulture, University of Georgia, 1111 Miller Plant Sciences, Athens, GA 30602, USAIn 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 (106 CFU/64 cm2), and after drying, populations were reduced by >2–3 log CFU/64 cm2. 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, UVAB 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.http://www.sciencedirect.com/science/article/pii/S0362028X25000109Dropped produceFoodborne pathogensGround contactPlastic mulchPreharvest food safetyVegetables
spellingShingle Autumn R. Burnett
Faith Critzer
Timothy Coolong
Quantification of Escherichia coli Transfer from Plastic Mulch to Field-grown Tomatoes and Bell Peppers
Journal of Food Protection
Dropped produce
Foodborne pathogens
Ground contact
Plastic mulch
Preharvest food safety
Vegetables
title Quantification of Escherichia coli Transfer from Plastic Mulch to Field-grown Tomatoes and Bell Peppers
title_full Quantification of Escherichia coli Transfer from Plastic Mulch to Field-grown Tomatoes and Bell Peppers
title_fullStr Quantification of Escherichia coli Transfer from Plastic Mulch to Field-grown Tomatoes and Bell Peppers
title_full_unstemmed Quantification of Escherichia coli Transfer from Plastic Mulch to Field-grown Tomatoes and Bell Peppers
title_short Quantification of Escherichia coli Transfer from Plastic Mulch to Field-grown Tomatoes and Bell Peppers
title_sort quantification of escherichia coli transfer from plastic mulch to field grown tomatoes and bell peppers
topic Dropped produce
Foodborne pathogens
Ground contact
Plastic mulch
Preharvest food safety
Vegetables
url http://www.sciencedirect.com/science/article/pii/S0362028X25000109
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