Total, water-soluble and acid-soluble arabinoxylans in western Canadian barleys

Abstract

Non-starch polysaccharides, such as β-glucan and arabinoxylan, are often implicated as a cause of the poor feeding value of barley for poultry. Levels of arabinoxylan in Canadian barley types, though, have not been thoroughly investigated. Total, water-extract and acid-extract arabinoxylan levels were determined for six-rowed (covered), two-rowed (covered) and hulless (both six- and two-rowed) barley (Hordeum vulgare) cultivars and genotypes grown in the 1991 Western Canadian Barley Cooperative Program. Analyses were performed using a dichromatic modification of the orcinol method. The six-rowed barley types contained significantly greater total, water-extract and acid-extract arabinoxylan concentrations than hulless or two-rowed types (P < 0.05). In hulless barley, total (P < 0.01), water-extract (P < 0.01), and acid-extract (P < 0.05) levels of arabinoxylan were, respectively, less than, greater than and similar to levels of arabinoxylan in samples of two-rowed barley. Environment had a significant effect on levels of water-extract (P < 0.01) and acid-extract (P < 0.05) arabinoxylan. Genetic differences affected the arabinoxylan content of cultivars and genotypes within each of the barley types (P < 0.05). Levels of acid-extract arabinoxylan were positively correlated with the viscosities of acid extracts of the barleys (P < 0.001). Key words: Arabinoxylan, barley, viscosity, acid-extract, pentosans