Survival of Salmonella Typhimurium, Listeria monocytogenes, and their surrogates on cantaloupes after triple-washing with peroxyacetic acid

The study aimed to evaluate the survival of Salmonella Typhimurium, Enterococcus faecium , Listeria monocytogenes , and Listeria innocua on cantaloupes during storage and after triple-wash exposure (water-water-antimicrobial) with peroxyacetic acid (PAA). Bacteria were spot-inoculated onto cantaloupe surfaces prior to triple-washing for 45 s at each washing step using 0, 27, 54, and 96 ppm of PAA. Spread-plating and a modified most-probable-number (MPN) method were utilized for enumeration of cells. Results showed that D-values (pre-wash) for S . Typhimurium (2.47 h) on cantaloupes were lower ( P < 0.05) than E. faecium (28.41 h), and the D-values (pre-wash) of L. monocytogenes (4.50 h) is also lower ( P < 0.05) than L. innocua (7.24 h). Though all tested concentrations of PAA resulted in significant ( P < 0.05) reduction of bacteria cells compared to the inoculated unwashed control, the greatest ( P < 0.05) reduction of S. Typhimurium and E. faecium (4.55 vs 3.23 log 10 CFU/cm 2 and 3.38 vs 2.55 log 10 MPN/mL) occurred at 96 ppm. This concentration (96 ppm) also achieved 3–4 log reductions of L. monocytogenes and L. innocua population. Results suggest that E. faecium could be used as surrogate of S. Typhimurium and L. monocytogenes for antimicrobial washing validation studies on cantaloupes. • PAA triple wash (WWA) effectiveness was compared for reducing pathogenic vs. surrogate bacteria on cantaloupe. • Survivors were enumerated using spread plating and estimated by MPN. • Log reductions of pathogenic vs surrogate Listeria were not statistically different. • Log reductions of E. faecium were statistically less than Salmonella Typhimurium. • PAA triple wash (WWA) at 96 ppm for 45 s at each step resulted in 3–4 log reductions.