Content, structure and viscosity of soluble arabinoxylans in rye grain from several countries

Abstract

AbstractRye grains from Finland, Canada, Sweden and Poland were extracted, during starch hydrolysis, with sodium acetate buffer at 95°C and soluble polymers were isolated by ethanol precipitation. The amount of sugar residues in the isolated polymers varied from 2.3 to 4.1% of rye dry matter with arabinose xylose and glucose residues predominant. High‐field H‐NMR analysis revealed that arabinoxylan I, containing terminal arabinose and un‐ and mono‐substituted xylose residues, and arabinoxylan II, containing terminal arabinose and un‐ and double‐substituted xylose residues, together with mixed‐linked (1 −3), (1 −4)‐β‐D‐glucans, were the dominating features in all samples of soluble polymers. On average, 46% of the xylose residues in arabinoxylan I and 57% in arabinoxylan II were substituted and the degree of substitution in the respective polymers was similar for all samples. The average content of arabinoxylan I ranged from 1.4% in samples from Canada to 1.7% in the Swedish samples and that of arabinoxylan II from 0.6% in samples from Poland to 1.0% in the Canadian samples.The viscosity of the soluble polymers was measured at a shear rate of 100 s−1. It was shown by partial least‐squares regression that in these samples the content of structural units characteristic of arabinoxylan II had a stronger correlation to viscosity than those of arabinoxylan I.