Corn oil is also a feedstock used for biodiesel. Almost all corn oil is expeller pressed, then solvent extracted using hexane or 2-methylpentane (isohexane). Alkali treatment also neutralizes free fatty acids and removes color (bleaching). This is a more expensive product since it has a much lower yield than the combination expeller and solvent process, as well as smaller market share. Some specialty oil producers manufacture unrefined, 100% expeller pressed corn oil.