两种分子质量水溶性半纤维素的制备及其对淀粉消化抑制作用研究

Preparation of two molecular weight water-soluble hemicelluloses and its inhibition on starch digestion

为了提升玉米加工副产品麸皮中水溶性半纤维素(corn bran hemicellulose,CBH)在功能性面制品中的综合利用,以玉米麸皮为原料,提取水溶性半纤维素CBH-L(CBH-Low)和CBH-H(CBH-High),并利用红外光谱(Fourier transform infrared spectroscopy,FT-IR)、凝胶渗透色谱(gel permeation chromatography,GPC)和离子色谱(high performance anion exchange chromatography-pulsed amperometric detecter,HPAEC-PAD)等对其分子结构和单糖组成进行表征。研究了剪切速率、温度等因素对半纤维素水溶液流变学特性的影响;通过淀粉消化试验建立胃肠道环境下半纤维素的表观黏度与小麦抗性淀粉(resistant starch,RS)比例之间的构效关系。结果表明,CBH-L分子质量(1.9×10^(3) Da)低于CBH-H的分子质量(5.1×105 Da);红外光谱图显示,两种半纤维素均具有多糖的典型特征。两种半纤维素水溶液均表现出良好的抗剪切性,且质量分数低于4.8%时具有一定的温度抗逆性。CBH-H相比于CBH-L对小麦淀粉消化性表现出更强的抑制作用,Pearson相关分析表明,小麦抗性淀粉比例的上升与半纤维素黏度成正相关关系,相关系数R=0.89(P<0.1)。研究显示,具有抑制淀粉消化功能的水溶性半纤维素有望成为功能性食品新原料。

This paper aimed to improve the comprehensive utilization of water-soluble corn bran hemicelluloses(CBH)in the by-product of corn processing in functional flour products.The study extracted water-soluble hemicelluloses CBH-low(CBH-L)and CBH-high(CBH-H)from corn bran.Fourier transform infrared spectroscopy(FT-IR),gel permeation chromatography(GPC),and high-performance anion-exchange chromatography-pulsed amperometric detecter(HPAEC-PAD)characterized their molecular structure and monosaccharide composition.The effects of shear rate and temperature on the rheological properties of hemicellulose aqueous solution were studied.The starch digestion test established the structure-activity relationship between the apparent viscosity of hemicellulose and the starch resistance ratio(RS)of wheat in the gastrointestinal environment.Results showed that the molecular weight of CBH-L(1.9×10^(3) Da)was lower than that of CBH-H(5.1×105 Da).FT-IR analysis showed that the two hemicelluloses had typical characteristics of polysaccharides.The two hemicellulose aqueous solutions showed good shear resistance and temperature stress resistance when the concentration was lower than 4.8%.Compared with CBH-L,CBH-H had a stronger inhibition effect on the digestibility of wheat starch.Pearson correlation analysis showed that the increase in the RS ratio of wheat starch was positively correlated with hemicellulosic viscosity,with a correlation coefficient of R=0.89(P<0.1).The water-soluble hemicellulose,which can inhibit starch digestion,provides new raw materials for functional food development.