D-glucan from hull-less barley ( Hordeum vulgare L. var. nudum Hook. f.)]]>

摘要

A high purity of β-D-glucan (80.8%) from hull-less barley (Hordeum vulgareL. var.nudumHook. f.) (HBBG) was isolated by alkali extraction and multi-precipitation with ethanol. The molecular weight (Mw) of HBBG was determined as 571.4?kDa with a broad distribution (Mw/Mn?=?1.6) by using HPSEC. According to methylation and GC-MS analysis, HBBG was identified to be composed of (1?→?4)- and (1?→?3)-glucopyranosyl (Glcp) residues with a ratio of (3.19?±?0.01). The MALDI-TOF MS and NMR spectroscopy were further conducted to analyze the enzyme hydrolysate released by lichenase digestion on HBBG. The results suggested that HBBG possessed a typical chemical structure of cereal β-D-glucans, namely linear homopolysaccharides formed by β-D-Glcpunits via (1?→?4)-linkages and occasionally single (1?→?3)-linkage. The trisaccharide and tetrasaccharide of HBBG accounted for 66.6% of total cellulosyl units, accompanying with a ratio of cellotriosyl to cellotetraosyl units?=?1.0, which were significant different from those reported for the other cereal β-glucans. Rheological property analysis revealed that HBBG showed a shear-thinning behavior and thermal resilience during heating-cooling process.