亚麻籽胶相对分子质量测定及单糖组成分析

Determination of relative molecular mass and monosaccharide composition of flaxseed gum

建立了尺寸排阻色谱法测亚麻籽胶相对分子质量的方法,并通过糖腈乙酸酯衍生化气相色谱法测定了亚麻籽胶的单糖组成。采用TSKgel G5000PWXL、TSKgel G3000PWXL二柱联用,超纯水为流动相,流速1.0 m L/min,进样浓度2.0 mg/m L,柱温40℃,配合蒸发光散检测器对葡聚糖标准品及样品进行了分析,结果表明不同分子量葡聚糖峰位洗脱时间与分子量对数值之间有良好的线性关系(R2=0.9842),精密度、重现性、稳定性及准确度良好,采用此法测得热水浸提、微波辅助热水浸提及市售亚麻籽胶峰位分子量分别为7793、2420、10392/6166/89183 ku,并给出了Mn、Mw、Mz及D值。单糖组成结果表明自制亚麻籽胶由鼠李糖、阿拉伯糖、木糖、半乳糖和葡萄糖组成,市售胶另含有甘露糖与岩藻糖,自制与市售胶在单糖种类和含量上有较大差异。

High performance size exclusion chromatography （HPSEC）method was established to determine the relative molecular mass of flaxseed gum.Subsequently, monosaccharide composition of flaxseed gum was analyzed by gas chromatography after derivatization with aldononitrile acetate.Combined SEC columns of TSKgel G5000 PWXL and TSKgel G300OPWxL, under conditions that ultrapure water as mobile phase, flow rate of 1.0 mL/min, sample concentration of 2.0 mL/min, column temperature of 40 ℃ and equipped with an evaporative light scattering detector, the relative molecular mass of dextran standards and flaxseed gum samples were determined. Results demonstrated that there was a good linear relationship between elution time and log M （R2 = 0.9842 ）.Precision, repeatability, stability and accuracy of this method were all acceptable. Relative molecular mass of flaxseed gum from hot water extraction process, microwave assisted hot water extraction process and commercially available were 7793,2420, 10392/6166/89183 ku respectively. Mn, Mw, Mz and D were also calculated. Monosaccharide composition analysis indicated that flaxseed gum that self-prepared were composed of rhamnose, arabinose, xylose, galactose and glucose, while commercially available flaxseed gum contained mannose and fucose in addition. Monosaccharide composition of flaxseed gum from different sources were quite different.