Biodegradable antifungal coating based on chitosan and citrus essential oil for the conservation of papaya (Carica papaya L.) in postharvest

Papaya is a highly perishable climacteric fruit. Anthracnose, a disease provoked by fungus, is one of the main causes of postharvest losses. The activity of plant extracts has allowed the in-hibition of the development of microorganisms; in particular, the antifungal activity of essen-tial oils has been reported. The aim of this re-search was to evaluate the effect of a biodegra-dable antifungal coating based on chitosan with citrus essential oil in the physicochemical and physiological properties and the antifungal ac-tivity of postharvest papaya (Carica papaya L.). The coating was prepared with chitosan, glyce-rol, acetic acid, essential oil of Citrus reticulata (0.5 %, 1.0 % and 1.5 %) and Tween (R) 80. The so-lution was applied with a brush to the epidermis of the postharvest papaya fruits and stored at room temperature (24 degrees C +/- 2 degrees C) for 10 d. The variables evaluated in the fruits were color, pH, degrees Brix, firmness, weight loss, production of CO2 and ethylene and anthracnose damage. An ana-lysis of variance (ANOVA) was performed un-der a completely randomized design and a com-parison of Tukey means (P < 0.05). The coating applied delayed the color change of the epider-mis of the papaya fruits, these maintained the high firmness values with respect to the control fruits. The changes were associated with the modification of the respiration rate and ethyle-ne production of the coated fruits. The chitosan matrix containing essential oils used as a coa-ting significantly improved shelf life of papa-ya and decreased anthracnose damage by 80 %.