Liid vegetable oils are converted to solid margarine by the use of

Liquid vegetable oils are converted into solid margarine through a chemical process known as hydrogenation [1]. Vegetable oils typically consist of long unsaturated carbon chains containing double bonds [1]. During hydrogenation, hydrogen gas is added across these double bonds in the presence of a metal catalyst, such as nickel, palladium, or platinum [1]. This reaction converts unsaturated hydrocarbons into saturated ones, effectively raising the melting point of the oil so that it becomes solid or semi-solid at room temperature. In commercial margarine production, the degree of hydrogenation is carefully controlled to achieve the desired spreadable consistency. While other gases like nitrogen are used to prevent oxidation and rancidity in food packaging [2], and oxygen is involved in the natural oxidation of fats [2], only hydrogen gas is used to chemically transform the oil's structure into a solid fat.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > 4.3.3 Addition Reaction > p. 71
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 1: Chemical Reactions and Equations > 1.3.2 Rancidity > p. 13