Determination of trans 2-nonenal in beer.

Wang, P.S. and Siebert, K.J.

Abstract
In this method the beer is extracted with methylene chloride, the 2,4 dinitrophenylhydrazones are prepared and then separated by column chromatography. The column, after separation, was cut into sections and each section was then subjected to thin layer chromatography. After development the bands corresponding to 2 nonenal and 2 undecenal (added to beer as an internal standard) were removed and extracted with chloroform. Alternatively high resolution liquid chromatography was used instead of thin layer. The identity of the 2 nonenal was confirmed by mass spectrometry. Using this method small amounts of 2 nonenal (0.03 ppb) were detected in fresh beer. Significantly large amounts (0.19 ppb) were found in beers which were papery to the taste. It was also found that the exposure of beer or beer extract to acidic conditions (lower than pH 4) artificially produces large amounts of 2 nonenal.
Keywords: analysis beer flavour 2 nonenal papery thin layer chromatography