Saponification is a chemical reaction that involves the hydrolysis of an ester in the presence of an inorganic base to produce an alcohol and the salt of a carboxylic acid. The reaction is usually used to refer to the soap-forming reaction of a metallic alkali (base) with fat or grease. The general reaction is as follows: Ester + Base → Soap + Alcohol. During saponification, triglycerides are reacted with potassium or sodium hydroxide (lye) to produce glycerol and fatty acid salt, called ‘soap’ . The saponification value or saponification number refers to the amount of base that is required to saponify a fat sample. Saponification is named after the fact that soap has long been made by the hydrolysis of fats (esters) .