Explain the importance of saponification.

Saponification is the hydrolysis of fats or oils under basic conditions to afford glycerol and the salt of the corresponding fatty acid ... It is important to the industrial user to know the amount of free fatty acid present, since this determines in large measure the refining loss.

Saponification occurs when a fat is heated with a strong base such as sodium hydroxide (NaOH) to give glycerol and the sodium salts of the fatty acids, which is soap.