Isolation of barley hulls and straw constituents and study of emulsifying properties of their arabinoxylans

Both barley hulls and straw contain valuable arabinoxylans and other useful carbohydrate and non-carbohydrate components. The functional water soluble non-caloric arabinoxylan (hemicellulose B) fraction was isolated from hot water-extracted and de-starched barley hulls and straws by an alkaline hydrogen peroxide extraction followed by ethanol precipitation. Barley hulls contained comparatively more Hemi. B (20.51%) than barley straws (7.41 to 12.94%). The sugar composition of Hemi. B showed that they were typical arabinoxylans containing (in addition to arabinose and xylose) some galactose, glucose and acidic sugars in the side chains. The hemicellulose B fractions from barley straws were superior oil-in-water emulsifiers than those from barley hulls. These Hemi. B fractions contain protein, which contributes to their emulsions stabilizing property.