Hydrogenation is the chemical process by which liquid vegetable oil is transformed into solid fat. The process involves treating the oil with hydrogen; it is a chemical reaction between molecular hydrogen (H2) and another compound or element (usually the oil molecules). Hydrogenation also increases the shelf life and the flavor stability of oils and foods that contain them. An oil can be either fully hydrogenated or partially hydrogenated. Fully hydrogenated oils are solid, while partially hydrogenated oils are semi-solid (the consistency of margarine or butter). Partially hydrogenated oils were recently taken of the FDA’s GRAS list because they contain trans fatty acids, or trans fats, which are harmful for our health. A fully hydrogenated oil doesn’t contain trans fats in the same way and are the new alternative to PHOs; when blended with liquid oils they make a semi-solid state.