Microencapsulation of clove essential oil improves its antifungal activity against Penicillium digitatum in vitro and green mould on Navel oranges

Abstract

ABSTRACT​Relatively high levels of clove essential oil (CEO) necessary for in vivo inhibition of postharvest pathogens imply that its antifungal activity should be reinforced. Hence, this study aimed to determine whether microencapsulation technology enhances the antifungal activity of CEO against Penicillium digitatum, the causal agent of citrus green mould, in vitro and on Navel oranges. Microencapsulation of CEO resulted in a respective reduction of minimum inhibitory concentration and minimum fungicidal concentration from 500 μg/ml to 125 μg/ml and 250 μg/ml, indicating the enhancement of fungistatic and fungicidal activity with respect to that of the pure oil. CEO microcapsules had the best control of lesion diameter and decay development (0.79 mm, 8.64%) in Navel oranges after 5 days’ storage at 25°C, followed by pure oil treatment (4.2 mm, 55.56%). In the vapour phase, CEO microcapsules also exhibited the highest ability to control green mould of Navel oranges. Furthermore, CEO microcapsules showed stronger suppressive activity of spore germination and germ tube elongation of P. digitatum than pure oil. These results indicate that the antifungal activity of CEO was considerably enhanced when it was converted into a microcapsule.