Antifungal Effect of Ocimum gratissimum on Fungi Associated with Retailed Cashew Nuts in Lokoja, Kogi State

Abstract

Post-harvest handling practises predispose cashew nuts to fungal contamination, leading to the production of mycotoxins that are harmful to human and animal health. Consequently, effective conservation methods are essential to reduce mycotoxin prevalence. The emergence of resistance to synthetic preservatives and their associated side effects has prompted the exploration of natural botanicals as alternatives. This study evaluated the antifungal effect of Ocimum gratissimum on fungi associated with retailed cashew nuts. Plant material was collected from the Biological Garden of Federal University Lokoja and extracted using the cold maceration technique. The poisoned food technique was employed to assess the efficacy of the extract. Results revealed that cashew nut samples had a fungal load ranging from 1.86 × 106 CFU/ml to 3.10 × 106 CFU/ml. The identified fungal isolates included Aspergillus flavus, Fusarium solani, and Candida tropicalis. The highest zones of inhibition were observed at 100% extract concentration, with 51.1% inhibition against Aspergillus flavus, 70.3% against Fusarium solani, and 67.1% against Candida tropicalis. Variations in inhibition zones may be attributed to differences in the cellular composition of the fungal isolates. This study concludes that Ocimum gratissimum extract exhibits significant antifungal activity against the tested organisms. The study recommends the use of Ocimum gratissimum as a natural antifungal preservative for cashew nuts, given its bioactive compounds that inhibit fungal growth.