物理改性对小米水溶性膳食纤维的结构表征及硒化能力的影响

利用超声-微波萃取、超微粉碎及二者协同处理分别对小米进行物理改性，以探究小米中水溶性膳食纤维的结构、阳离子交换能力和硒结合能力。结果表明：改性后的小米水溶性膳食纤维的化学基团无明显变化，晶体结构未被破坏，表面疏松多孔，呈颗粒状，其中超微粉碎协同超声-微波萃取改性使小米水溶性膳食纤维表现出较明显的特征吸收峰，分子质量降低，X-衍射峰宽度增加，超微粉碎改性使水溶性膳食纤维粉体颗粒分布密集，出现团聚的现象；四种小米水溶性膳食纤维的阳离子交换能力分别为1.59 mmol/g，1.00 mmol/g，1.69 mmol/g，0.99 mmol/g，其中超微粉碎协同超声-微波萃取改性能显著提高小米水溶性膳食纤维阳离子交换能力，与硒结合能力有所改善。综上，超微粉碎协同超声-微波萃取改性可有效提高小米水溶性膳食纤维的阳离子交换能力并对硒化修饰具有促进作用。

Effects of Physical Modification on the Structural Characterization and Selenization Ability of Millet Water-soluble Dietary Fiber

The millet was physically modified by ultrasonic-microwave extraction, superfine pulverization, and the two co-processing. It is used to explore the structure, cation exchange capacity and selenium binding capacity of water-soluble dietary fiber in millet. The results shown that the chemical groups of millet SDF had no obvious changes, the crystal structure wasn''t destroyed, the surface was loose and porous, and they were granular. However, the combination of superfine grinding and ultrasound-microwave made the millet SDF present more obvious about the characteristic absorption peak, the molecular weight was reduced, besides, the X-diffraction peak width was increased, and the ultrafine crushing made the SDF powder particles distributed densely and agglomerated; the cation exchange capacity of the four millet SDFs were 1.59 mmol/g, 1.00 mmol/g, 1.69 mmol/g, 0.99 mmol/g, of which the combination of superfine grinding and ultrasonic-microwave could improve the SDF cation exchange capacity of millet significantly, and also well in terms of its ability to combine with selenium. In summary, the combination of superfine grinding and ultrasonic-microwave treatment of raw materials could improve the cation exchange capacity of millet SDF, and also have a significant impact on the binding capacity with selenium.