Abstract:
Essential oils which are the volatile components distilled from the aromatic
plant materials, have gained importance in cosmetic, therapeutic, aromatic, fragrant
and spiritual uses. But the conventional methods of distillation carry the disadvantages
mainly concerned with the quality of final product such as loss of some volatile notes,
low extraction efficiency and degradation of unsaturated ester compounds through
thermal or hydrolytic effects. These processes also requires high extraction times and
energy consumption. However, in order to reduce these difficulties microwave energy
could be effectively used to mediate extraction of essential oil in place of steam or
water heating in order to introduce its inherent advantages. As in the case of microwave
heating of food materials, the internal heating of the in-situ water within the plant
material by the microwaves leads to the rupture of the glands and oleferous receptacles
freeing the essential oil which is then evaporated by the in-situ water of the plant
material. The water then evaporated could then be passed through a condenser outside
the microwave cavity where it is condensed. This study envisages development of a
microwave assisted extraction system for extracting nutmeg mace essential oil. The
developed extraction system consists of a microwave cavity, extraction unit, supporting
stand and energy meter. In order to evaluate the developed system towards extraction
of nutmeg mace essential oil, the process parameters like solid: water ratios of 1: 14,
1: 10 and 1:6, power densities of 9.6, 14.4 and 19.2 W/g and soaking times of 2, 3 and
4 h which would influence the essential oil yield, extraction time and energy
consumption were chosen as independent variables.
The physical quality
characteristics like refractive index, specific gravity, solubility and colour of essential
oil were selected as dependent variables. The optimized conditions of solid: water
ratio, power density and soaking time for extracting nutmeg mace essential oil in
microwave assisted process was found to be 1: 14, 14.4 W/g and 4 h respectively.
Therefore, microwave assisted extraction could be considered as an extraction
technique that results in the production of high quality oil in higher quantity in less
time with minimum energy consumption.
