De Man Wannes L, Vaneeckhaute Ewoud, De Brier Niels, Wouters Arno G B, Martens Johan A, Breynaert Eric, Delcour Jan A
Laboratory of Food Chemistry and Biochemistry and Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Kasteelpark Arenberg 23, B-3001 Heverlee, Belgium.
COK-KAT, KU Leuven, Celestijnenlaan 200F-box 2461, B-3001 Heverlee, Belgium.
J Agric Food Chem. 2021 Apr 7;69(13):3912-3922. doi: 10.1021/acs.jafc.1c00180. Epub 2021 Mar 29.
The structural heterogeneity of water-extractable arabinoxylan (WE-AX) impacts wheat flour functionality. H diffusion-ordered (DOSY) nuclear magnetic resonance (NMR) spectroscopy revealed structural heterogeneity within WE-AX fractions obtained via graded ethanol precipitation. Combination with high-resolution H-H correlation NMR spectroscopy (COSY) allowed identifying the relationship between the xylose substitution patterns and diffusion properties of the subpopulations. WE-AX fractions contained distinct subpopulations with different diffusion rates. WE-AX subpopulations with a high self-diffusivity contained high levels of monosubstituted xylose. In contrast, those with a low self-diffusivity were rich in disubstituted xylose, suggesting that disubstitution mainly occurs in WE-AX molecules with large hydrodynamic volumes. In general, WE-AX fractions precipitating at higher and lower ethanol concentrations had higher and lower self-diffusivity and more and less complex substitution patterns. Although H DOSY NMR, as performed in this study, was valuable for elucidating WE-AX structural heterogeneity, physical limitations arose when studying WE-AX populations with high molecular weight dispersions.
水可提取阿拉伯木聚糖（WE-AX）的结构异质性影响小麦粉的功能特性。氢扩散排序（DOSY）核磁共振（NMR）光谱揭示了通过分级乙醇沉淀获得的WE-AX组分中的结构异质性。与高分辨率氢-氢相关NMR光谱（COSY）相结合，能够确定木糖取代模式与亚群扩散特性之间的关系。WE-AX组分包含具有不同扩散速率的不同亚群。具有高自扩散率的WE-AX亚群含有高水平的单取代木糖。相比之下，那些具有低自扩散率的亚群富含双取代木糖，这表明双取代主要发生在具有大流体力学体积的WE-AX分子中。一般来说，在较高和较低乙醇浓度下沉淀的WE-AX组分具有较高和较低的自扩散率，以及较复杂和较简单的取代模式。尽管本研究中进行的氢DOSY NMR对于阐明WE-AX结构异质性很有价值，但在研究具有高分子量分散性的WE-AX群体时出现了物理限制。
