What reduces unsaturated vegetable oils to form a solid product?

Unsaturated vegetable oils can be reduced to form a solid product through a process called hydrogenation. In this process, hydrogen gas is added to the oil in the presence of a catalyst, typically nickel, at elevated temperatures and pressures. This reaction converts some of the double bonds in unsaturated fatty acids to single bonds, resulting in a more saturated fat that is solid at room temperature. The degree of hydrogenation can be controlled to achieve the desired texture and melting point of the final product.