Efficacy of Peroxyacetic Acid and Sulfuric Acid-Surfactant Blends for Reducing Listeria monocytogenes Contamination on the Surface of Whole Cantaloupes

The continued occurrence of foodborne illness outbreaks linked to cantaloupes highlights the need for additional efforts to mitigate the risk of pathogen contamination on these products before they reach consumers. This study evaluated the efficacy of a sanitizer blend consisting of peroxyacetic acid (PAA) and a proprietary sulfuric acid-surfactant (SS) (PAA-SS) in reducing inoculated L. monocytogenes populations on whole cantaloupe melons. Cantaloupes (n = 6) were surface-inoculated (ca. 8 log CFU/cantaloupe) with a five-strain mixture of L. monocytogenes and then immersed in water, 40 ppm free chlorine (CL), SS at pH 1.8, PAA (40, 80, and 250 ppm; denoted as PAA40, PAA80, and PAA250, respectively), or PAA-SS (pH 1.8; denoted as PAA40-SS, PAA80-SS, PAA250-SS) for 0.5, 1, or 5 min. Regardless of exposure time, L. monocytogenes reductions obtained with CL and all the PAA and PAA-SS treatments were greater (P < 0.05) than those obtained with the water treatment. Overall, irrespective of treatment time, reductions ranged from 2.1 to 3.3 log CFU/cantaloupe for CL, 0.9 to 1.8 log CFU/cantaloupe for SS, 3.0 to >4.6 log CFU/cantaloupe across the three PAA concentrations, and 3.2 to >4.9 log CFU/cantaloupe across the three PAA-SS blends. In general, the efficacy of PAA40-SS, PAA80-SS, PAA250-SS, and PAA250 was greater (P < 0.05) than that of the CL treatment. Furthermore, the effectiveness of the PAA-SS blends was largely comparable (P ≥ 0.05) to that of PAA (without SS) applied at the same concentration and exposure time. However, the absence of surviving populations (<2.7 log CFU/cantaloupe detection limit) in some samples treated with PAA250-SS suggested that combining PAA with the sulfuric acid-surfactant may enhance the antimicrobial effects of PAA. The results of this study offer alternatives to chlorine for reducing L. monocytogenes contamination on the surface of cantaloupes and highlight the potential application of PAA-SS blends in produce sanitizer systems.