Biochemical activity of Ocimum gratissimum essential oil against fruit-rotting fungi Penicillium expansum and Penicillium digitatum

Abstract

The fruit-rotting fungi Penicillium expansum and Penicillium digitatum are the primary cause of postharvest losses as they cause blue mold of apples and green mold of oranges, respectively. In addition to rotting, they also contaminate food with their highly toxic chemical known as patulin, which is well known for its carcinogenic effect. In the present study, the essential oil of Ocimum gratissimum obtained by hydro-distillation was tested for its antifungal assay against P. expansum and P. digitatum in in vitro culture conditions. 500 ppm MIC of the essential oil completely inhibited the mycelial growth of both the test fungi in vitro. The inhibitory effect of the essential oil was also observed directly on the fruits, apples and oranges inoculated with P. expansum and P. digitatum spore suspensions in vivo. They were fumigated with the essential oil of O. gratissimum for 10 days and the results obtained showed potent biochemical activity up to 93 % against blue mold rot of apples and up to 75 % against green mold rot of oranges. The present study suggests use of Ocimum oil as a safe, effective and alternative means to control fruit rotting fungi.