Submitted to: International Journal of Postharvest Technology and Innovation
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/27/2013
Publication Date: 8/12/2013
Citation: Picard, I., Hollingsworth, R.G., Wall, M.M., Nishijima, K., Salmeiri, S., Vu, K., Lacroix, M. 2013. Effects of chitosan-based coatings containing peppermint essential oil on the quality of post-harvest papaya fruit. International Journal of Postharvest Technology and Innovation. 3:178-189. Interpretive Summary: Papayas are being exported from Hawaii to the U.S. mainland, Canada, and Japan. Thus, an extended shelf-life allows the fruits to be exported longer distances while maintaining market quality. Edible coatings are a potential treatment that may minimize postharvest losses caused by dehydration, discoloration, softening, and decay. A promising edible bioactive coating was identified that combines unmodified chitosan with a low concentration of peppermint oil. Papaya fruits treated with this formulation showed a slightly higher sugar content, low weight loss, no peel injury, and 100% marketable fruits.
Technical 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 discoloration, less color 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 less peel discoloration than the experimental control and 100% of the fruits were marketable. The modified chitosan apparently increased the hydrophobicity of the coating resulting in a loss of firmness and delayed color development of coated fruits during ripening.