Chemical Properties
Roasted coffee beans consist of soluble and insoluble products. Under laboratory conditions, it is possible to extract a
high percentage of the soluble compounds, whereas in normal household brews, this percentage is likely to be only 15 to 25%. Yields
and concentrations vary widely due to differences in beans, the size of the grinds, type of brewing process and degree of roasting. In
general, home brewing of coffee uses 42, 48 and 57 g of ground, roasted coffee per liter of water in the United States, United Kingdom
and Europe, respectively. Therefore, the final beverage consists of <2% w/w soluble products of coffee. Soluble coffee extract is the
product consisting of the dried solids prepared from a water extract or water extracts of coffee.
Composition
Aroma extract dilution analysis revealed 13 compounds as important contributors to the aroma of the roasted coffee:
2-methyl-3-furanthiol, 2-furfurylthiol, methional, 3-mercapto-3-methylbutylformate, 3-isopropyl-2-methoxypyrazine, 2-ethyl-3,5-
dimethylpyrazine, 2,3-diethyl-5-methylpyrazine, 3-isobutyl-2-methoxypyrazine, 3-hydroxy-4,5-dimethyl-2(5H)-furanone (sotolon),
4-ethylguaiacol, 5-ethyl-3-hydroxy-4-methyl-2(5H)-furanone, 4-vinylguaiacol and (E)-beta-damascenone
Taste threshold values
Taste characteristics at 500 ppm: bitter, astringent roasted coffee with burnt brown hydrolyzed vegetable
protein nuances and a lingering bitter coffee aftertaste.
