we have the evolution of the extraction yield, as a function of the extraction time. The experiments were performed at atmospheric pressure and optimal operating conditions (600 W). An extraction time of 30 min with ESFME provided yield comparable to those obtained after 37 min with conventional SFME and 180 min with hydrodistillation.Consequently, the main advantage of the ESFME process was its rapidity. The overall yield of essential oils obtained
from fennel seeds was 0.48% by the ESFME and 0.46% by both conventional SFME and hydrodistillation methods.These yields were high in comparison with the yield of fennel essential oil obtained by Jigar Patel et al. (2012) (0.4%) by improved microwave assisted extraction.