Saponification value

[1][2][3] It is a measure of the average molecular weight (or chain length) of all the fatty acids present in the sample in form of triglycerides.

The higher the saponification value, the lower the fatty acids average length, the lighter the mean molecular weight of triglycerides and vice versa.

To determine saponification value, the sample is treated with an excess of alkali (usually an ethanolic solution of potassium hydroxide) for half an hour under reflux.

[4]: 98  At the end of the reaction the quantity of KOH is determined by titration using standard solution of hydrochloric acid (HCl).

2 For instance, triolein, a triglyceride occurring in many fats and oils, has three oleic acid residues esterified to a molecule of glycerol with a total MW of 885.4 (g / mol).

3) is not applicable to fats and oils containing high amounts of unsaponifiable material, free fatty acids (> 0.1%), or mono- and diacylglycerols (> 0.1%).

[7] Unsaponifiables are components of a fatty substance (oil, fat, wax) that fail to form soaps when treated with alkali and remain insoluble in water but soluble in organic solvents.