Determination of Aldehydes in Wines by the Direct Bisulfite Method: American Society of Enologists—AOAC Joint Report

Abstract

Abstract A collaborative study was made on the Guymon and Crowcll direct bisulfite determination of aldehydes in wine in cooperation with a committee of the American Society of Enologists. The method is based upon the reaction of the aldehydes with an excess of bisulfite solution at a neutral pH, removal of the excess bisulfite by iodine in acid medium, and direct titration with standard 0.05/V iodine of the bisulfite released in alkaline medium. The mean values for aldehydes found in 4 wines by 9 collaborators gave standard deviations of 2,7-4.5% of the mean. The method determines free aldehydes plus aldehydes bound with bisulfites existing in wines, while it excludes acetals which account for only 1-3% of the aldehydes present. The method gives a very satisfactory degree of precision and accuracy and is recommended for adoption as official, first action