Ghee

Yogic practices such as pranayama, hatha yoga (asanas), mudras (hand gestures), bandhas (energy locks), meditation, brahmacharya (abstinence), and ahimsa (non-violence) all lead to the creation of physical heat in the body.  This is more than physical heat as it is a pranic, mental, or spiritual heat, psychic in nature. It is also known as ‘tapas’ (to burn, create heat or to produce energy). Just as Ghee is offered in fire ceremonies due to its effect of increasing the fire, Yogis use ghee to increase purifying heat in both body and mind. Just as a burnt seed becomes incapable of reproducing, when the mind is totally pure it becomes incapable of producing more reincarnations and liberation takes place. 

Ghee holds its position of purity in nearly all the Hindu pooja rituals. In Hindu mythology, Prajapati/Brahma, created Ghee by rubbing or "churning" his hands together and then poured it into fire to engender his progeny. So, whenever the Vedic rituals are performed, the pouring of Ghee into fire symbolises a re-enactment of creation.