Impact of Reused or New Plastic Mulch on Survival of Escherichia coli and Transfer to Tomato and Bell Pepper Fruit

Autumn R Burnett^1*Blanca Ruiz-Llacsahuanga²Faith Critzer²Timothy Coolong¹

• ¹University of Georgia Department of Horticulture, Athens, GA, United States
• ²University of Georgia Department of Food Science and Technology, Athens, GA, United States

This study determined survival of the surrogate Escherichia coli TVS 353 GFP on reused plastic mulch (double-cropped) versus new plastic mulch (single-cropped) and transfer to fruit with ground contact in a field setting. Fruit ground contact treatments included dropped fruit treatments from various heights (30, 60, and 120 cm) and “drooping” treatments (fruit that is still attached to the plant, but touches the ground) for a duration of 1 or 24 h. When comparing survival on shaded versus unshaded locations on plastic mulch, survival over 24 h of E. coli on all locations and mulch types was reduced greater than 3.5 log CFU/64 cm2. At 4 h after inoculation, reused plastic mulch retained significantly less E. coli than new mulch at both locations under canopy (shaded) and on the exterior (unshaded) (P<0.05). Plastic mulch in drooping fruit treatments transferred low amounts of E. coli to fruit (0.01-0.03% of dried inoculum) with no significant differences between reused or new plastic mulch or duration of contact (P<0.05). Likewise, there was low transfer (0.02-1.87%) from plastic mulch to dropped fruit. Transfer to dropped fruit was affected by treatment including reused or new type of mulch, crop, and height. These results provide information to shape future regulations and risk assessments in preharvest foodborne pathogen contamination, as well as indicate food safety implications for the sustainable practice of reusing plastic mulch.