Title: Fresh produce washing aid, T-128, enhances inactivation of Salmonella and pseudomonas biofilms on stainless steel coupons in chlorinated wash solutions Authors
Submitted to: International Association for Food Protection
Publication Type: Abstract Only
Publication Acceptance Date: April 8, 2012
Publication Date: July 22, 2012
Citation: Shen, C., Luo, Y., Nou, X., Zhou, B., Bauchan, G.R., Wang, Q., Millner, P.D. 2012. Fresh produce washing aid, T-128, enhances inactivation of Salmonella and pseudomonas biofilms on stainless steel coupons in chlorinated wash solutions. [abstract]. Technical Abstract: Introduction: Bacterial biofilms on food processing equipment can protect pathogens against sanitizers. When chlorine is rapidly depleted by organic materials present in process wash water, inactivation of biofilm pathogens is further challenging. Purpose: This study was conducted to evaluate the efficacy of chlorinated water (CW) solutions, with or without the washing aid, T-128, on inactivation of Salmonella and Pseudomonas in biofilms on stainless steel in the presence of increasing organic matter loads. Methods: Biofilms were formed statically on stainless steel coupons suspended in 2% lettuce extract after inoculation with Salmonella enterica serovars Thompson or Newport, or Pseudomonas fluorescens. Coupons with biofilms were washed in CW (0, 0.5, 1, 2, 5, 10, or 20 mg/L at pH 6.5, 5.0 and 2.9), with or without T-128, and with increasing loads of organic matter (0, 0.25, 0.5, 0.75, or 1.0% lettuce extract). Cell populations on coupons were dispersed using intermittent pulsed-ultrasonication-vortexing, and enumerated by colony counts on XLT-4 or Pseudomonas agars. Cell responses to fluorescent viability staining after washing treatments were examined using confocal laser-scanning microscopy. Statistical analysis was performed using SAS PROC Mixed procedure. Results: 0.1% T-128 (without chlorine) reduced P. fluorescens biofilm populations by 2.5 logs, but did not reduce Salmonella populations. For both bacteria, the sanitizing effect of free chlorine (1.0-5.0 mg/L) was enhanced (P<0.05) by approximately 1.0-3.0 logs when combined with T-128. Application of T-128 decreased free chlorine depletion rate caused by increasing organic matter in CW, and significantly (P<0.05) augmented inactivation of biofilm bacteria. Staining with SYTO 9/propidium iodide corroborated the cultural assay results showing that T-128 can aid in reducing pathogen viability in biofilms. Significance: T-128 reduced pathogen viability in biofilms when used in CW containing high loads of organic matter. Thus, it can aid in sanitizing surfaces by removing bacterial biofilms during fresh-cut produce processing.