Efficacy of plant-derived compounds combined with hydrogen peroxide as antimicrobial wash and coating treatment for reducing Listeria monocytogenes on cantaloupes

The efficacy of four plant-derived antimicrobials (PDAs), namely carvacrol, thymol, β-resorcylic acid, and caprylic acid, with or without hydrogen peroxide (HP), as antimicrobial wash and chitosan based coating for reducing Listeria monocytogenes (LM) on cantaloupes was investigated. Cantaloupe rind plugs inoculated with LM (10⁷CFU/cm²) were washed for 3, 6, 10min at 25°C or 1, 3, 5min at 55 or 65°C in water, or water containing 2% PDAs with or without 2% HP. Additionally, inoculated cantaloupes (10⁸CFU/fruit) washed with 2% PDA-HP combinations at 55 or 65°C (5min) were cut into rindless cubical pieces, stored at 4°C for 7 days and sampled for LM. Furthermore, inoculated plugs coated with 2% PDAs were stored for 7 days and sampled for surviving LM. Individual PDA washes reduced LM on rinds by 2.5logCFU/cm² by 3min (P<0.05). PDA-HP combinations decreased LM to undetectable levels by 5min at 55, 65°C, and 10min at 25°C (P<0.05) and reduced LM transfer from cantaloupe surface to interior (P<0.0001). All PDA coating treatments reduced LM on cantaloupe to undetectable levels by 5 days (P<0.05). Results indicate that PDAs alone, or with HP could be used to reduce LM on cantaloupes.