This test method is a procedure used to determine the acid value (AV) of fats and oils. The acid value measures the amount of free fatty acids (FFA) present, which indicates the degree of hydrolytic rancidity or degradation in the fat or oil. The acid value is an important quality parameter because high FFA levels can negatively affect flavor, stability, and shelf life of edible fats and oils. A weighed amount of the fat or oil is dissolved in a neutral solvent mixture, then titrated with a standard solution of potassium hydroxide (KOH) using a phenolphthalein indicator until a faint pink endpoint is reached. The acid value is calculated as the number of milligrams of KOH required to neutralize the free fatty acids in 1 gram of sample.