Control of postharvest fungal decay in papaya fruits by chitosan-carboxymethyl cellulose coating incorporated with essential oilsãnd potassium sorbate

Abstract

The objective of this study was to evaluate the effect of plant essential oils in combination withãcid salts for development of edible coating formulations. Firstly,ãntifungalãctivities of cinnamon (Cinnamomum verum), clove (Syzygiumãromaticum),ãnd collaãromatica Roxb. (Homalomenaãromatica) oilsãndãcid salts (ammonium carbonate, potassium metabisulfite,ãnd potassium sorbate) were studied. Cinnamonãnd clove oilsãt 0.0125-0.2% minimum inhibitory concentration (MIC) were effective to inhibit growth of Aspergillus flavus TISTR 3041, Penicillium citrinum TISTR 3437,ãnd 2 mold strains, Talaromyces sp. P2D4ãnd Aspergillus sp. P8A6 isolated from papaya fruits, while those salts showedãntifungalãctivityãt 0.5-8% MIC. Combination of cinnamon or clove oil with potassium sorbate showed the synergistic effectãgainst Talaromyces sp. P2D4. Effect of cinnamon or clove oil combined with potassium sorbate in 0.1% chitosanãnd 0.25% carboxymethyl cellulose (ChiCMC) coating on controlling postharvest fungal decay in papaya fruits during storageãt 30°C for 8 days was studied. Synergistic combinations of 0.0397% clove oil combined with 0.25% potassium sorbate, or 0.25% cinnamon oil combined with 1% potassium sorbate in the ChiCMC coating were effective to delay fungal decay in papaya fruits. At the end of storage, these coatings significantly showed less decay incidence (53.3-56.7%) compared toã control treatment (100% decay incidence). Thus, use of cinnamon or clove oil combined with potassium sorbate in the ChiCMC coating could potentially be used in the postharvest management for decay control in papaya fruits.