What is the process called when hydrogen is added to oil to make it solidify?

The process of adding hydrogen to oil to make it solidify is known as hydrogenation. This chemical reaction involves the addition of hydrogen atoms to unsaturated fatty acids, which can convert liquid oils into more solid forms, such as margarine or shortening. This transformation is crucial in the food industry, as it alters the texture and stability of fats, making them suitable for various culinary uses.

In contrast, emulsification refers to the process of mixing two immiscible liquids, such as oil and water, to create a stable mixture, but it does not change the physical state of the fats. Refining involves purifying oil to remove impurities and can include physical and chemical processes, but it does not specifically refer to the hydrogenation process. Oxidation involves the reaction of fats with oxygen, leading to rancidity and degradation, which is the opposite of solidifying oils. Therefore, hydrogenation is correctly identified as the process that solidifies oil by introducing hydrogen.