Novel antimicrobials to control foodborne pathogens on cantaloupe

Authors: Patel, Jitu; UPADHYAY, ABHINAV - University Of Connecticut; VENKITANARAYANAN, KUMAR - University Of Connecticut

Submitted to: United States-Japan Cooperative Program in Natural Resources
Publication Type: Proceedings
Publication Acceptance Date: 11/1/2016
Publication Date: 11/7/2016
Citation: Patel, J.R., Upadhyay, A., Venkitanarayanan, K. 2016. In: Novel antimicrobials to control foodborne pathogens on cantaloupe. United States-Japan Cooperative Program in Natural Resources Conference Proceedings, November 7, 2016. p.29-30.

Interpretive Summary: Multi-state disease outbreaks due to consumption of cantaloupes contaminated with Salmonella and Listeria monocytogenes have been reported in the U.S. Current industrial practice of cantaloupe wash with chlorine results in minimal reductions in pathogen populations. ARS researchers investigated the efficacy of a new generation disinfectant, namely octenidine dihydrochloride (OH) as pre- and post-harvest wash and coating treatments for reducing disease causing bacteria on cantaloupe surface. Pre-harvest treatment of OH reduced L. innocua and E. coli O157:H12 at 14 days post inoculation. All post-harvest OH wash treatments reduced L. monocytogenes, Salmonella spp. and E. coli O157:H7 on cantaloupe rinds by > 5 log CFU/cm2 in 2 min. The chitosan-based coating of OH on cantaloupe rinds reduced the pathogens by 3 to 5 log CFU/cm2. Washing whole cantaloupes for 5 min with 0.1 and 0.2% OH decreased pathogen populations by at least 5 log CFU/cm2. The OH could be effectively used as pre- and post-harvest wash and coating treatments to reduce L. monocytogenes, E. coli O157:H7, and Salmonella spp. on cantaloupes and enhance food safety.

Technical Abstract: This study investigated the efficacy of a new generation disinfectant, namely octenidine dihydrochloride (OH) as pre- and post-harvest treatment for reducing Listeria monocytogenes, Salmonella spp., and Escherichia coli O157:H7 on cantaloupe surface. At farm, cantaloupes were dip-inoculated with L. innocua or E. coli O157:H12 followed by spraying of OH (0.1-0.2%). Cantaloupes were harvested at 14 and 28 days post inoculation (dpi)to determine surviving populations of pathogens. For post-harvest study, cantaloupe rind plugs inoculated separately with L. monocytogenes, Salmonella spp., or E. coli O157:H7 (~8 log/cm2) in laboratory were washed for 1, 3, or 5 min at 25°C in sterile water (control), chlorine (200 ppm) or water containing OH (0.01, 0.05, 0.1%), and surviving pathogen populations were enumerated. Additionally, inoculated cantaloupe rind plugs were coated with 2% chitosan or chitosan containing OH (0.01, 0.05, 0.1%) and sampled for surviving pathogen populations. Subsequently, the efficacy of OH wash and coating treatments (0.1 and 0.2%) in inactivating the three pathogens on whole cantaloupes was determined. Treatment of cantaloupe with OH at farm reduced E. coli O157:H12 by 6 log MPN and L. innocua by 2 long MPNat 14 dpi. All post-harvest OH wash treatments reduced L. monocytogenes, Salmonella spp. and E. coli O157:H7 on cantaloupe rinds by > 5 log CFU/cm2 by 2 min, and decreased their counts to undetectable levels (below 2 log CFU/cm2) by 5 min (P < 0.05). Similarly, OH coating on cantaloupe rinds reduced the pathogens by 3-5 log CFU/cm2. Washing whole cantaloupes for 5 min with 0.1 and 0.2% OH decreased pathogen populations by at least 5 log CFU/cm2 (P < 0.05). Moreover, chitosan-based OH coating at 0.1 and 0.2% decreased all three pathogen populations on whole cantaloupes. Results indicate that OH could be effectively used as pre- and post-harvest treatments to reduce foodborne pathogens on cantaloupes and enhance food safety.