Cereal Chem 66:107-111   |  VIEW ARTICLE

Physico-Chemical and Functional Properties of Rye Nonstarch Polysaccharides. I. Colorimetric Analysis of Pentosans and Their Relative Monosaccharide Compositions in Fractionated (Milled) Rye Products.

J. A. Delcour, S. Vanhamel, and C. De Geest. Copyright 1989 by the American Association of Cereal Chemists, Inc. 

The water-soluble, enzyme-extractable, and total pentosans (WSP, EEP, and TP, respectively) of rye kernels were estimated by a modification of the orcinol-hydrochloric acid method of Hashimoto et al (1987a). Modifications included absorbance readings both at 670 and 580 nm to minimize the small but significant interference by hexose sugars in the analytical figures and appropriate dilution of the pentosan extracts before analysis, as rye contains more pentosans than wheat. The relative monosaccharide ratios in the different milling extracts were estimated by gas chromatography of the alditol acetates of the monosaccharides released upon hydrolysis of the pentosan extracts. The highest proportion of TP was in the bran, whereas the shorts contained the highest proportion of both the WSP and the EEP. The proportion of WSP and EEP relative to the TP varied widely. D-(+)-Xylose and L-(+)-arabinose were the most abuncant monosaccharides, along with significant amounts of D-(+)-glucose. D-(+)-Galactose, and D-(+)-mannose were present in trace amounts. The WSP in different milling fractions had smaller variations in the arabinose/xylose ratios (0.76-0.81) than was observed for the EEP (0.58-0.80) and TP (0.74-1.09). The EEP and TP were relatively richer in xylose for the bran and the short fractions as opposed to what was found for the fine flour fractions.