ISO International Standard

The method comsists in preparing of a test solution by adding water to test portion, in the case of products containing more than 10 mg of free sulphur dioxide per litre, adding of acetaldhyde, then adding of p-toluidine and barbituric acid solution to an aliquot potion of the test solution, thus forming a red coloration by reaction with 5-hydroxymethylfurfural present, and spectrometric measuring at a wavelenght of 550nm.