VOLATILE MINOR ACIDS IN COFFEE .2. DETECTION OF STEAM TREATMENT

The contents of butanoic, 2-methylpropanoic, pentanoic, (S)-2-methyl-b utanoic and 3-methylbutanoic acids have been determined in several pai rs of steam treated and not treated samples of medium roasted coffee b y capillary gas chromatography after preparing an infusion with hot wa ter and clean-up by precipitation with methanol, freeze-drying and sim ultaneous distillation/extraction (SDE). Contents of the treated sampl es are lower in most cases. For detection of steam treatment, 3-methyl butanoic acid and, in the second place, (S)-2-methylbutanoic acid are suited best, because in every case their contents are lowered by treat ment, and because the reductions are more pronounced than those of the other acids.