Comparison of wire and plastic belts on microbial attachment and biofilm formation

Food processing equipment is subject to attachment of bacteria, which can lead to product contamination, spoilage, and surface destruction. Prevention of bacterial contamination during processing of poultry products is a major concern for food processors. During processing of poultry products, bacteria from the carcass can attach to wet surfaces which can lead to biofilm formation providing a source for cross contamination for subsequent carcasses. The purpose of this study was to determine susceptibility to bacterial attachment and biofilm formation with and without poultry products of different conveyor belts including polyurethane with mono polyester fabric, acetal (3.2 % open mesh), polypropylene- mesh top (24% open mesh), polypropylene (48% open mesh), stainless steel – single loop (80% open mesh) and stainless steel – balance weave (70% open mesh). To perform the sanitizer efficacy against attached bacteria on different conveyor belts test chips were prepared. Test chips were made in duplicate and inoculated with raw chicken. One test chip was removed to check aerobic plate count and coliform count while other test chip was exposed to quaternary ammonia (200 ppm). Except polyurethane with mono polyester fabric others belts showed significant reduction (P < 0.05) after exposed to sanitizer. Surfaces were inoculated with Salmonella / Listeria monocytogenes cocktail (without any poultry product) in BPW to achieve final inoculum level of 5 log CFU/ml. Test surfaces were analyzed by sponge and swab method at 0, 1, 2, 4, 6, 8, 12, 24 and 48 hr. Initial attachment (0 hr) of Salmonella / Listeria monocytogenes did not show any significant (P < 0.05) change in all belt types; however, polyurethane with mono polyester fabric belts showed a significant attachment over time. Attachment of bacteria with poultry products was determined with test chips. Poultry products were inoculated with Salmonella or Listeria monocytogenes culture for one hour and rinsed with PBS. Test chips were immersed in this solution and evaluated for 1, 6, 12, 24 and 48 hr, through vortexing with glass beads. At 1 and 48 hr, attachment of Salmonella and Listeria monocytogenes was lowest in the stainless steel single loop, and stainless steel –balance weave. Attachment of Listeria monocytogenes to form a biolfim was determined. Initial biofilm formation was very low on the stainless steel belts but by day 4 all belts had all belts showed significant biofilm formation. An increased understanding of bacterial attachment and biofilm formation with respect different design of conveyor belts will assist in the development of interventions to counter act these processes and thereby, enhance plant sanitation and pathogen control.