CONTRIBUTION OF BIOSENSORS TO ENOLOGY AND CONSTRAINTS ASSOCIATED WITHTHEIR USE

In order to improve the quality of wine, the winemaker has to follow m alolactic fermentation (decarboxylation of L-malic acid) and to avoid D-lactic acid formation. Amperometric biosensors specific to these two acids are proposed. They are made of an enzyme layer adapted to the s ubstrate near a platinum electrode and they enable the conversion of t he substrate concentration into an electrolysis current intensity. The assay is fast and cheap, and the apparatus is very simple. These sens ors are used to follow the winemaking process, but most of the results are different from the values obtained by enzymatic spectrophotometri c measurements because there is an interfering compound in wine which is responsible for a non-enzymatic reaction. To palliate this interfer ence, two measurements are performed with the same sensor, the first o ne with enzymatic solution in the reaction chamber, the second one wit hout any enzyme. Using this procedure, a good agreement with enzymatic spectrophotometric measurements is obtained.