Steam distillation is the preferred method for all essential oils produced in large quantity. Direct steam distillation is the most efficient method. In this method instead of making the steam in the kettle it is prepared in a boiler and then passed through the bed of ginger at a certain pressure. The steam extracts most of the essential oil and hence, this method is most economical and quick.
First of all, ginger is cut into smaller pieces with the help of a cutting machine. Usually this cutting operation is carried out manually. Manual operation is most suitable for a small scale unit. After cutting of ginger, pieces are beat with the help of a hammer to break the oil cells. Now these pieces of ginger are fed on a wire gauge, which is fixed in a mild steel kettle. After preparing the bed, the outlet of the kettle is connected to a water cooler and the outlet of the condenser is connected to the collecting pot.
The steam at is passed into the kettle from the bottom. The steam passed through the pores of the ginger bed and extracts the volatile oil with it. This extractor is carried out until hole of the volatile oil is extracted. The vapor of water and oil condenses in the condenser and falls into the collection pot. These pots are generally made of glass. In the pot, two layers are formed after the condensed vapors are settled. Water layer remains on lower side while oily layer floats on the water. Oil is separated from tin pot. Thus oil obtained by this method contains about 5 to 6% water.
For separating the ginger oil, oil water mixture is subjected to reduce pressure distillation. Crude oil is taken in a flask like kettle and some arrangement are made as stated above for distillation process. A vacuum pump is connected in series in order to create vacuum. Now the flask is heated and pump is switched on when the required temperature is reached, the vapors of oil start coming out and these vapors are collected in a pot by condensing them in a condenser.
When all the volatile oil comes out, then the temperature of the mixture in the flask starts rising and at that stage collection of vapors should be discontinued. The ginger oil is packed in 760ml. glass bottles. This packing is done manually. An air tight seal is provided to prevent the loss of oil through volatilization.
