Acid value / free fatty acids (FFA)

A small aliquot of oil is dissolved in a neutral solution of IMS & toluene. This solution is titrated against a standard potassium hydroxide solution using phenolphthalein as an indicator.

Method used BS 684, Section 2.10
Units Acid value -
mg KOH/g oil

FFA - %
(usually quoted as oleic acid)
Significance of result
The acidity of an oil is dependent on the amount of free fatty acids present. This in turn is dependent on the degree of hydrolysis of the oil or the nature of the processing which the oil may have undergone. Refined oils are often referred to as neutralised, ie they have a low acidity. Raw and crude oils are naturally hydrolysed and consequently have a higher acid value.

The acidity may be measured as either the acid value (or acid number) or as the free fatty acid (FFA).

Flask and Gloves