Abstract
The cell wall of wild rice (Zizania palustris) was fractionated by the conventional method, affording pectin (7%), hemicellulose (71%), and cellulose (22%). The hemicellulose content was markedly higher than that of cultivated rice, while the pectin content was lower. Soluble hemicellulose was further fractionated by DEAE column chromatography to provide three components: H1, H2, and H3. High-performance anion exchange chromatography and methylation analysis suggested that H1 was a neutral arabinoxylan, with a lower degree of branching than that in rice, H2 was a glucuronoarabinoxylan, and H3 was a pectic polysaccharide containing a galacturonan backbone. Thus the unique texture of wild rice might be ascribable to the high content of hemicellulose and the lower branching of arabinoxylans compared to the cell wall hemicellulose of cultivated rice. The dietary fiber effect of hemicellulose in the wild rice cell wall is an important feature that should be investigated further.
