Die Röstkaffee-Flüssigextraktion zur Herstellung von Löslichem Kaffee im Modellversuch. II. Zeitlicher Verlauf des Überganges von Säuren, Kohlenhydraten sowie 5-Hydroxymethyl-2-furfural (HMF) in den Flüssigextrakt

During roast coffee extraction the yield of acids is proportional to the extraction degree. Thereby, the contents of formic acid, chinic acid and acetic acid are more increasing than that of citric and malic acid. This is the reason for a qualitative and quantitative change of acidic taste in the course of extraction... Opposite to roast- and ground coffees, the investigated coffee extracts contained free carbohydrates in low concentrations. In the beginning of extraction above all arabinose is released. In the second phase of extraction, mannose and galactose are dissolved by hydrolytic cleavage of mannanes and galactanes. These hydrolyses are of special importance for the content of dry matter during instant Coffee production. 5-Hydroxymethyl-2-furfural and 2-furfural are formed from carbohydrates during the extractin process. The total liquid coffee extract investigated in this paper contained the 3,5-fold amount of these furaldehydes than the ground coffee which was used for ts production.