Ghani technology is the traditional method of extraction of oil from oil seeds like sesame, mustard, rapeseed etc. by use of simple technology. In this technology, oilseeds are held in scoped circular pit in the center of mortar made of stone or wood. In it works a stout upright pestle which descends from tip curved or angled piece. The pestle rests in a scooped out hollow that also permits pestle to rotate. Today the single angled piece takes the form of two shorter pieces chained together. The bottom of lower angled piece is attached to a load beam. One end of load beam rides around the outside of barrel while other is yoked to animal. The load beam is weighted down either with heavy stones or even seated operator. As the animal moves in circular ambit, the pestle rotates exerting lateral pressure on the upper chest of the pit, first pulverizing the oilseed and then crushing out its oil.
Oil yield in Ghani technology:
An oil rich seed such as sesame seed or groundnut yields about 5 percent less oil in ghani than in modern expeller mainly because of insufficient pressure. Ghani oil-seed cake carries about 15 % residual fat, about twice that of screw press oil-seed cake. In fact in modern days, oil-seed cake produced by crushing rape and mustard seeds in ghani is put through screw press to obtain 2 % oil.