ISO 3657:2013 specifies a method for the determination of the saponification value of animal and vegetable fats and oils. The saponification value is a measure of the free and esterified acids present in fats and fatty acids.
The method is applicable to refined and crude vegetable and animal fats.
If mineral acids are present, the results given by this method are not interpretable unless the mineral acids are determined separately.
The saponification value can also be calculated from fatty acid data obtained by gas liquid chromatography analysis as given in an annex. For this calculation, it is necessary to be sure that the sample does not contain major impurities or is thermally degraded.