Arabinoxylan (HBAX-60) was fractioned from alkaline-extracted arabinoxylan (HBAX) in the whole grain of hull-less barley (Hordeum vulgareL.var. nudumHook. f.Poaceae) by 60% ethanol precipitation, which was studied for physicochemical properties and structure elucidation. Highly purified HBAX-60 mainly composed of arabinose (40.7%) and xylose (59.3%) was created. The methylation and NMR analysis of HBAX-60 indicated that a low-branched β-(1→4)-linked xylan backbone possessed un-substituted (1,4-linked β-Xylp, 36.2%), mono-substituted (β-1,3,4-linked Xylp, 5.9%), and di-substituted (1,2,3,4-linked β-Xylp, 12.1%) xylose units as the main chains, though other residues (α-Araf-(1→, β-Xylp-(1→, α-Araf-(1→3)-α-Araf-(1→ or β-Xylp-(1→3)-α-Araf-(1→) were also determined. Additionally, HBAX-60 exhibited random coil conformation in a 0.1 M NaNO3solution. This work provides the properties and structural basis of the hull-less barley-derived arabinoxylan, which facilitates further research for exploring the structure–function relationship and application of arabinoxylan from hull-less barley.Keywords:hull-less barley;arabinoxylan;structural characteristics
Yong Xie,Qingqing Liu,Haibo Liu,Zhiping Fan,Jia Shi,Xiong Liu
The favorable prebiotic effect of cereal β-glucans is associated with its structure characteristic, which may be influenced by thermal processing. This study aimed to evaluate the structure and in vitro fermentation characteristics of β-glucan isolated from hulless barley preprocessed with flaking-roasting (FR), stir-frying (SF), steam-flash explosion (SFE) and popping expansion (PE). The results showed that all thermal processing had no impact on the type of chemical groups. Compared with the native β-glucan, the molecular weight of PE-β-glucan increased from 147.36 × 10 3 Da to 5, 243.60 × 10 3 Da, whereas its crystallinity index decreasing from 52.9 ± 0.7% to 41.5 ± 1.1%. Furthermore, the PE-β-glucan exhibited a porous structure like that in native β-glucan, while the SFE-β-glucan displayed a compacted structure with the lowest molecular weight (89.90 × 10 3 Da). Expectedly, PE-β-glucan exerted the highest availability and increased the relative abundance of Bifidobacterium , while FR-, SF-, and SFE-β-glucan tended to promote the growth of Megasphaera and Lactobacillus . Additionally, the level of total SCFAs, acetate, propionate , and butyrate in PE-β-glucan were dramatically higher than those in other β-glucan. Overall, the chain conformation of β-glucan played a pivotal role in determining its bioavailability and probiotic characteristic, which could be improved evidently by PE processing.
危险品化学品经营许可证（带存储）