Determination of Sorbic Acid in Wine

Abstract

Abstract A survey of a number of laboratories engaged in wine analysis showed that 2 basic techniques were used for the determination of sorbic acid. The first utilizes the absorbance by sorbic acid at 260 nm in acidic solution and the second depends on the oxidation of sorbic acid to malonaldehyde which is then reacted with thiobarbituric acid. The resulting red color is measured at 532 nm. A modification of the thiobarbituric method has been adopted by AOAC for the determination of sorbic acid in cheese. We found it could be successfully utilized for sorbic acid analysis in wine with minor changes. It was necessary to separate the sorbic acid from wine by steam distillation prior to either determination. The standard Cash wine volatile acid still is adequate for this purpose and over 9 9% acid could be recovered from a 2 ml wine sample in 200 ml distillate. We studied various parameters in both techniques and arrived at practical procedures for each. Both methods gave acceptable results and we recommend that they be subjected to a collaborative study.