hydrogenated

Hydrogenated is an adjective used in chemistry to describe a substance that has had hydrogen added to it, typically across carbon–carbon double bonds in organic compounds. The process, hydrogenation, is a reduction reaction that converts unsaturated compounds to more saturated ones and can change physical properties such as melting point and stability.

In industry, hydrogenation is widely used to convert liquid oils into semi-solid or solid fats. This is achieved by exposing oils to hydrogen gas in the presence of a metal catalyst, commonly nickel, at elevated temperature and pressure. Hydrogenation can be partial or complete. Partial hydrogenation adds hydrogen to some double bonds but can isomerize existing cis double bonds into trans configurations, producing trans fats. Fully hydrogenated fats have all carbon–carbon bonds saturated with hydrogen, resulting in a higher melting point and typically a solid fat at room temperature.

Applications extend beyond food to chemical manufacturing, where hydrogenation is used to reduce alkenes, carbonyl compounds, and to prepare saturated products. Catalysts vary and may include nickel, palladium, or platinum on suitable supports; conditions are adjusted to control degree of saturation and selectivity.

Health, safety, and regulation: Partially hydrogenated oils contain trans fats that have been linked to adverse health effects, especially cardiovascular disease. Many countries require labeling of trans fats or have phased them out of foods; some have banned partially hydrogenated oils. As a result, manufacturers often substitute non-hydrogenated or fully hydrogenated fats, or use alternative fat-modification methods.

History: Hydrogenation of fats became widespread in the 20th century as a method to improve stability and texture of products like margarine, baker's shortenings, and processed foods.