Scientific journal

48 2009

Journal of Food and Nutrition Research
Summary No. 2 / 2009

A comparative study of arabinogalactan-protein isolates from instant coffee powder of Coffea arabica beans
Journal of Food and Nutrition Research, 48, 2009, No. 2, s. 80-86

Peter Capek, Institute of Chemistry, Center for Glycomics, Slovak Academy of Sciences, Dúbravská cesta 9, SK - 845 38 Bratislava, Slovakia. Tel.: +421-2-59410 209, fax: +421-2-59410 222, e-mail:

Summary: Parallel extraction of instant coffee powder prepared from roasted beans of Coffea arabica by industrial process according to the procedure of Wolfrom and Anderson afforded two arabinogalactan-protein isolates, i.e. AG1 and AG2 in yields of 14.6% and 14.4% of a crude polysaccharide complex A (w/w), respectively. However, their yields were about twice lower in comparison with AG isolation described by Wolfrom and Anderson forty years ago. Stronger roasting and extraction conditions during the industrial process used at that time for producing instant coffee powder used for AG isolation are supposed to be the main reason. This conclusion is supported by the fact that molecular masses of newly isolated arabinogalactans AG1 and AG2 were higher (5 200–5 400) then that of arabinogalactan isolated in the past (1 800 only). The presence of proteins in AG1 and AG2 suggests that these polysaccharides are present in the form of arabinogalactan-protein. Saccharide analysis of both polysaccharides showed similar composition: over 85% of galactose and 8% of arabinose residues, accompanied by smaller amounts of sugars as contaminants, which were not determined in previous isolation. Identical structure of both arabinogalactan-proteins was confirmed on the basis of 1H and 13C NMR spectra.

Keywords: Coffea arabica; roasted beans; instant coffee powder; arabinogalactan-protein; nuclear magnetic resonance; Fourier transform infrared spectroscopy

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