What is the chemical process that turns a liquid fat into a solid fat?

The process of hydrogenation is the correct choice because it involves adding hydrogen atoms to liquid fats, typically vegetable oils, which results in the conversion of these fats from a liquid state to a solid state. This chemical reaction alters the molecular structure of the fatty acids, leading to an increase in saturation—the more saturated a fat is, the more solid it tends to be at room temperature. Hydrogenated oils are utilized in various food products to improve texture, stability, and shelf life.

Emulsification is a different process that involves mixing two immiscible liquids, such as oil and water, to create a stable mixture. Oxidation refers to a reaction where a substance loses electrons, which often leads to spoilage in fats rather than converting them to a solid. Saponification is the reaction between a fat or oil and an alkali to produce soap, which also does not relate to the conversion of liquid fats into solid fats. Thus, hydrogenation is the specific chemical process that achieves the transformation in question.