Acetaldehyde as a possible indicator of spoilage in green kona (Hawaiian) coffee

Publisher Website
Google Scholar
Abstract
Kona coffee cherries were demucilaged by either mechanical, enzymic or chemical methods, by the action of bacterial pure cultures, or by natural fermentation. Thirteen volatile components were detected by gas chromatography in all samples of green coffee tested, and these included methanethiol, acetaldehyde, dimethyl sulphide, propionaldehyde, acetone, isobutyraldehyde, butyraldehyde, ethanol, and isovaleraldehyde. Probably, methanol and/or methyl ethyl ketone also were present among the volatile components detected.The relative concentrations of several volatile components did not vary appreciably among the different lots of coffee demucilaged experimentally. However, acetaldehyde concentration increased as the duration of natural fermentation was prolonged, being markedly higher in grossly over‐fermented (spoiled) coffee beans.All samples of coffee demucilaged experimentally had similar cup‐testing quality (Kona grade No. 1), indicating that none of the demucilaging methods enhanced or diminished coffee flavour or aroma. Over‐fermented beans, however, were poor in cup‐testing quality.