ISO 5519:1978

The method consists in homogenizing the product, followed by quantitative entraining, by steam, of the acid present in a test portion, determination of the acid in the destillate obtained, either by spectrophotometry in the ultra-violet range (technique A) or by measuring by photocolorimetry or by spectrophotometry the pink colour obtained after oxidation by chromic acid and then treatment with thiobarbituric acid (technique B).