An investigation of coffee roasting using high performance gel filtration chromatography

Abstract

Changes in the molecular weight distribution of components in green coffee during roasting were investigated using high performance gel filtration chromatography (HPGFC) with TSK-PW 4000 columns. The chromatographic separation of sample extracts obtained from green and roasted coffees, after different degrees of roasting, was monitored by refractive index (RI) detection and UV detection at 280, 325 and 420 nm. The chromatograms obtained with RI detection showed significant differences in molecular weight profiles. UV detection showed similar patterns at 280 and 325 nm, suggesting that phenolic compounds were probably bound to proteins. The formation of pigments was clearly demonstrated when chromatography was carried out with detection at 420 nm and the coloured material was found to be distributed throughout the molecular weight range studied. The use of HPGFC provided a more rapid analysis compared with traditional gel filtration and proved to be useful in monitoring changes in molecular weight which occur during coffee roasting. © 1986.