A high purity of β-D-glucan (80.8%) from hull-less barley (Hordeum vulgare L. var. nudum Hook. 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-Glcp units 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.

中文翻译：

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来自无壳大麦 (Hordeum vulgare L. var. nudum Hook. f.) 的 β-D-葡聚糖的结构表征和流变学特性

通过碱提取和乙醇多重沉淀从无壳大麦（Hordeum vulgare L. var. nudum Hook. f.）（HBBG）中分离出高纯度的 β-D-葡聚糖（80.8%）。通过使用 HPSEC，HBBG 的分子量 (Mw) 被确定为 571.4 kDa，具有广泛的分布 (Mw/Mn = 1.6)。根据甲基化和 GC-MS 分析，HBBG 被确定为由 (1 → 4)- 和 (1 → 3)-吡喃葡萄糖基 (Glcp) 残基组成，比例为 (3.19 ± 0.01)。进一步进行 MALDI-TOF MS 和 NMR 光谱分析由地衣酶消化在 HBBG 上释放的酶水解产物。结果表明，HBBG 具有谷类 β-D-葡聚糖的典型化学结构，即由 β-D-Glcp 单元通过 (1 → 4) 键和偶尔单 (1 → 3) 键形成的线性同多糖。HBBG 的三糖和四糖占总纤维素单位的 66.6%，同时纤维三糖与纤维四糖单位的比率 = 1.0，这与其他谷物 β-葡聚糖报道的有显着差异。流变性能分析表明，HBBG 在加热-冷却过程中表现出剪切稀化行为和热回弹性。