Gas chromatographic analysis of aldehydes in alcoholic beverages using a cysteamine derivatization procedure

A series of short-chain, volatile, and saturated aldehydes (C-1 to C-9) wer e quantified in wines, brandy, and sherry. These compounds are known to imp act alcoholic beverage quality as they contribute to overall flavor and the y affect aging and color stability. An analytical method was validated whic h specifically measured the aldehydes present in just one assay. This metho d was based on a derivatization process involving the reactions of aldehyde s with cysteamine (2-aminoethanethiol) at room temperature. A stable thiazo lidine derivative was formed from each of the reacted aldehydes. The thiazo lidine derivatives formed were extracted with cholorform then subsequently quantified by gas chromatography (GC) using a fused silica capillary column and a nitrogen-phosphorous detector (NPD). These procedures were used to a nalyze several red and white wines, brandy, and sherry; in addition to the predominant aldehyde - acetaldehyde - trace amounts of other aldehydes were also identified. The effects of derivatization and extraction at various p H levels to obtain free and bound aldehydes, and the effects of different l evels of SO2 and phenols on aldehyde recovery and precision were evaluated. Compared to the results from the standard AOAC distillation/titration meth od for aldehydes in wine, the cysteamine derivatization method was more acc urate and gave higher recoveries (similar to 40% higher).