Purpose: This study is to evaluate the removal of mixed P. fluorescens, L. monocytogenes, and S. typhimurium based biofilms on industrial food processing plant equipment by evaluating the efficacy of foam alkaline, chlorinated alkaline, neutral foam cleaners, and acidic foam cleaners. This was followed by either a sodium hypochlorite, chlorine dioxide, quaternary ammonia, or peroxyacetic acid sanitizer exposure.
Methods: Bacterial cultures were inoculated into dynamic low nutrient flow biofilm generator where biofilms formed and matured on suspended High Density Polyethylene (HDPE) coupons for 72h. Once the biofilms were established, the HDPE coupons were removed and exposed to a water rinse to remove any planktonic cells. The rinse was followed by various foam cleaner and sanitizer combinations. Following sanitization, coupons were fully neutralized in D/E broth and vortexed to remove the remaining viable sessile cells. Serial dilutions were plated onto Tryptone Soy Fast Green (TSAF) and compared against control coupons to determine log reductions.
Results: The experimental combinations tested to date, show the chlorinated alkaline cleaner with chlorine sanitizer combination having the highest reduction 6.63 log CFU/cm2, followed by the mild non-chlorinated alkaline cleaner followed by peroxyacetic acid at 4.98 log CFU/cm2. The least efficacious combination to date was the mild alkaline cleaner followed by the quaternary ammonia sanitizer at 1.64 log CFU/cm2.
Significance: The ability to replicate an immature or mature biofilm enables the experimenter to test a wide variety of cleaner-sanitizer combinations utilized in the removal of typical food plant biofilms. This enables one to create a functional database of the variety of cleaner and sanitizer combinations vs a variety of meat [in this case], dairy, and produce biofilms. It also has application for other food market plant biofilms as well.