Hydrogenation of oil :
long fatty acids of Unsaturated hydrocarbons add hydrogen in the presence of catalysts such as palladium or nickel to give saturated hydrocarbons.This reaction is commonly used in the hydrogenation of vegetable oils using a nickel catalyst.
Vegetable oils generally have long unsaturated carbon chains while animal fats have saturated carbon chains.
You must have seen advertisements stating that some vegetable oils are ‘healthy’.
Animal fats generally contain saturated fatty acids which are said to be harmful for health. Oils containing unsaturated fatty acids should be chosen for cooking.