In vitro and in vivo activity of essential oil from dill (Anethum graveolens L.) against fungal spoilage of cherry tomatoes

The objectives of present study were to determine the antifungal activity in vitro of the essential oil extracted from the seeds of dill (Anethum graveolens L.) and to evaluate its antifungal activity in vivo as a potential food preservative. The antifungal activity of this oil was tested by poisoned food technique against Aspergillus flavus, Aspergillus oryzae, Aspergillus niger and Alternaria alternata. The wet and dry mycelium weight of the tested fungi was also determined in a liquid culture to evaluate the antifungal activity. The minimum inhibitory concentration of oil for the four tested fungi was found to be 2.0 μl/ml, and the mycelial growth inhibition was determined at day 9. Observations on the microstructure of A. niger using light and scanning electron microscopes revealed degenerative alterations in the conidial heads and hyphal morphology after oil treatment, including distorted conidial heads, decreased hyphal diameters, shriveled hyphal aggregates, and swelling of the hyphal wall. The effect of the essential oil on inhibition of decay development on cherry tomatoes was tested in vivo by exposing inoculated and control fruit to essential oil vapor at 120 μl/ml and 100 μl/ml concentrations, respectively. Thus, the essential oil of dill could be used to control food spoilage as a potential source of food preservative.