Measurement of Volatile Aldehydes in Grapes, Wines and Musts

Using a cysteamine derivatization procedure and analysis with GC-Nitrogen Phosphorous Detection (GC-NPD) volatile, saturated aldehydes (C1-C9) in wine or aqueous ethanol can be accurately measured as their corresponding thiazolidine derivative. Using this procedure we have shown in preliminary experiments, that S02 additions during fermentation can effect the concentrations of a number of aldehydes. Further confirmatory studies are now in progress. We are also validating a separate method for the analysis of unsaturated aldehydes (e.g., acrolein) and dicarbonyls (malonaldehyde) in wines and distillates. The method is based on the reaction of these aldehydes with N-methylhydrazine to form methyl pyrazoline derivatives which can be analyzed by GC-NPD. In preliminary studies, we have obtained a limit of detection of 0.2 mg/mL and a limit of quantification of 0.5 mg/mL for acrolein and malonaldehyde. Spiked recoveries averaged 90 ± 12%for acrolein, malonaldehyde, and crotonaldehyde over a series of concentrations (2-20 mg/mL) in model wine and wine matrices.