Postharvest mycobial contaminants of white button mushroom (Agaricus bisporus) and their management using plant essential oils

Being highly perishable, mushrooms’ quality and shelf life is affected by various factors during postharvest conditions, among which fungal contamination is the main cause. The goal of this study is to identify and manage fungal contaminants present in mushrooms during postharvest conditions. A total of 23 fungi were isolated as contaminants from the samples of Agaricus bisporus collected from three major vegetable markets in Kathmandu city, Nepal. Aspergillus niger, Aspergillus flavus, and Rhizopus stolonifer were found to be the most frequent fungal contaminants. These were treated with various concentrations of essential oils (EOs) of Cinnamomum tamala, Mentha spicata, Zanthoxylum armatum, and Eucalyptus citriodora using poisoned food technique. Significant (p<0.05) inhibition of mycelial growth and spore germination was found in all testedfungi by all EOs. A strong inhibitory action of M. spicata oil was recorded against A. flavus and R. stolonifer while, A. niger was best controlled by C. tamala oil at the concentration of 20 µl/ml. These results suggest that EOs of three tested plants could be a good alternative to control fungal contaminants and extend the shelf life of Agaricus bisporus in postharvest conditions.