MODELING THE AQUEOUS EXTRACTION OF SOLUBLE SUBSTANCES FROM GROUND ROAST COFFEE

The kinetic results obtained by Zanoni et al (J Sci Food Agric 58 1992 275-279) for the extraction of solubles from sieved roast arabica coffee at 90-degrees-C have been recalculated and re-interpreted. It has been shown that the 85-90 % of solubles extracted within the first minute can be accounted for by diffusion of the soluble constituents through the coffee particles rather than by a large washing phase. It is also suggested that the subsequent slower extraction process may be caused by the emergence of different constituents according to the particle size.