Purpose: This study was conducted to evaluate the efficacy of chlorinated water (CW, with hypochlorous acid) solutions, with or without the washing aid, T-128, on inactivation of natural microbial flora, Salmonella enterica serovars Poona and Newport, Pseudomonas fluorescens, and Escherichia coliO157:H7 biofilms on cantaloupe rinds.
Methods: Biofilms were formed by spot-inoculation of pure- and co-cultured bacterial strains on cantaloupe rind surfaces, followed by 24-h storage at 22 °C. Cantaloupes were manually washed for 5 min or vigorously scrubbed with fruit brushes for 1 min in CW (200, 500, 800, 1000, or 2000 mg free chlorine (FC)/l at pH 5.0 or 2.8) with or without T-128. Cell populations on cantaloupe rinds were dispersed using intermittent pulsed-ultrasonication and stomaching, and enumerated using modified MPN or plating onto XLT-4 agar or petrifilms. Statistical analysis of data was performed using PROC Mixed procedure of SAS.
Results: In general, for natural microbial flora and bacterial biofilms, the FC (500-2000 mg/l) sanitizing effects were enhanced (P < 0.05) by approximately 1.0-2.0 log CFU/cm2 when combined with T-128, especially in 2000 mg/l CW with T-128, by manually washing. An additional reduction (P < 0.05) of 0.7-1.0 log CFU/cm2 of S. Poona or E. coliO157:H7 was observed in CW (500-1000 mg/l) with T-128 with the brush-scrubbing wash.
Significance: These results indicate that T-128 can aid in reducing pathogen viability in biofilms on cantaloupe rinds, and thereby can aid in reducing food safety risks associated with fresh cantaloupes.