More specifically, when used in non-sealed flasks, the free oils failed to prevent the fungal growth (even up to the high concentration of 1000 ppm), and the encapsulated form managed to do so at 950ppm which was much higher than its effective concentration under sealed condition (350 ppm)The deteriorating effect of open (non-sealed) condition could be ascribed to the evaporation of the oils.Hence, higher concentrations would be required to prevent the fungal growth under open condition.