Electrophoretic clean-up of organic acids from coffee for the GC/MS analysis.
The clean-up presented here includes a free flow field step electrophoresis followed by ultrafiltration. Thus, organic acids can be separated from non-acidic and high-molecular compounds in roasted and instant coffee. The acids are identified by gas chromatography/mass spectrometry after freeze-drying and trimethylsilylation. With the method presented, 31 acids could be identified in commercial roasted coffee blends and in instant coffee, among them for the first time in coffee: 3-hydroxypropionic, 2-oxobutyric, glyceric, 2,4-dihydroxybutyric, 5-hydroxymethylfuran-2-carboxylic and 2-hydroxyglutaric acid.
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Institut für Lebensmittelchemie der Technischen Universität Braunschweig, Schleinitzstrasse 20, D-38106, Braunschweig, Germany.
Maier
H G
HG