178 Int. J. Postharvest Technology and Innovation, Vol. 3, No. 2, 2013 Copyright © 2013 Inderscience Enterprises Ltd. Effects of chitosan-based coatings containing peppermint essential oil on the quality of post-harvest papaya fruit Isabelle Picard Research Laboratory in Sciences Applied to Food, INRS-Institut Armand Frappier, Canadian Irradiation Center, 531 Boulevard des Prairies, Laval, Quebec, H7V 1B7, Canada Robert G. Hollingsworth, Marisa Wall and Kate Nishijima U.S. Pacific Basin Agricultural Research Center, USDA-ARS, 64 Nowelo Street, Hilo, Hawaii, 96720, USA E-mail: Robert.Hollingsworth@ars.usda.gov E-mail: Marisa.Wall@ars.usda.gov E-mail: Kate.Nishijima@ars.usda.gov Stéphane Salmieri, Khanh Dang Vu and Monique Lacroix* Research Laboratory in Sciences Applied to Food, INRS-Institut Armand Frappier, Canadian Irradiation Center, 531 Boulevard des Prairies, Laval, Quebec, H7V 1B7, Canada Fax: +1-450-686-5501 E-mail: Stephane.Salmieri@iaf.inrs.ca E-mail: DangKhanh.Vu@iaf.inrs.ca E-mail: Monique.lacroix@iaf.inrs.ca *Corresponding author Abstract: Edible coatings comprised of antimicrobial polymers based on chitosan are promising technologies to preserve post-harvest fruit quality. In this study, we investigated the potential utility of a coating made from chitosan modified by N-acylation with fatty acid to preserve post-harvest papaya quality. Peppermint essential oil (EO) was added to the chitosan-based coatings as an antifungal agent. A formulation which contained a high concentration of peppermint EO (1.0%) without chitosan apparently damaged the peel, resulting in higher peel discolouration, less colour development and lower marketability. The most promising treatment was unmodified chitosan (1%) in combination with peppermint EO (0.2%). The fruits treated with this formulation showed