Acid value

The acid value (AV ) is a chemical parameter for the characterization of acidic components in fats. It means the mass of potassium hydroxide (in mg) needed to neutralize the free fatty acids contained in 1 g of fat. In addition to fatty acids can also be detected the presence of any mineral acids. But not the bound acids as glycerides are collected with as in the saponification. The determined free fatty acids give conclusion on decomposition processes or pretreatment. Unrefined crude oils have a SZ <10, whereas refined oils have a SZ <0.2. In practice, the sample is first dissolved in an organic solvent. Then the acids are titrated with potassium hydroxide to phenolphthalein.