Formation/Removal of Biofilms on/from Coupons of Selected Food-Grade Elastomeric Polymers vs. Plexiglass Used for the Fruit-Catching Plates of OTR Blueberry Machine Harvesters

Abstract

To reduce the bruising potential of machine-harvested fresh blueberries, manufacturers of over-the-row (OTR) machine harvesters are replacing the hard, plexiglass fruit-catching plates with soft, elastomeric polymers. This study assessed whether selected soft, food-grade elastomeric polymers, with the potential to be used in OTR harvesters, have a greater likelihood to encourage more microbial buildups, making cleaning/sanitation a greater challenge. Coupons of plexiglass, silicone, neoprene, and ethylene propylene diene monomer (EPDM) were exposed to fecal coliforms from various sources for biofilm development. The coupons with developed biofilms were treated with sodium hypochlorite, peracetic acid, isopropyl alcohol-based quaternary ammonium compounds (Alpet D2), or commercial dish soap. Biofilms and their residuals after the sanitizer treatments were quantified. The fecal coliforms isolated from the surface of OTR harvesters developed significantly (p ≤ 0.05) more biofilms than those from other sources. EPDM coupons had significantly more, while neoprene and silicone coupons had insignificantly different (p > 0.05) amounts of biofilms from plexiglass coupons. After sanitizer treatments, EPDM coupons had significantly more, while neoprene and certain silicon coupons had significantly fewer residues than plexiglass coupons. Study suggests that compared to plexiglass, neoprene and silicon did not support more microbial buildups or retain more biofilms after sanitizing treatments.