As for the coffee oil - the result of olives and coffee beans being pressed together by the Spanish olive oil producer Vea - again it is pungent, almost acrid.

It is during the roasting process that the sugars and other carbohydrates within the bean become caramelized, creating a substance which is known as the coffee oil.

Even after being subjected to the rigors of brewing, roughly 15 percent of the weight of dried coffee grounds is oil, which, much like palm and soybean oil, can be converted into biodiesel.