离子交换树脂纯化大豆糖蜜上清液

Purification of Soy Molasses Supernatant by Ion-Exchange Resins

大豆糖蜜上清液中除大豆低聚糖(蔗糖、棉子糖和水苏糖)外,还含有色素、无机盐、含氮组分和有机酸等杂质。本文主要研究了离子交换树脂纯化脱色糖蜜上清液过程中去除杂质的机理并优化了纯化工艺。结果显示:脱色上清液中主要的含氮组分有5种游离氨基酸(天冬氨酸、谷氨酸、天冬酰胺、丙氨酸、酪氨酸)和1种二肽(谷氨酸-酪氨酸)。用离子交换树脂直接处理脱色上清液的效率很低,含氮组分在3倍柱体积处理量时穿透;而离子交换树脂对纯含氮组分的吸附能力很强,处理量约为40倍柱体积。因此,无机盐(Na^+、K^+和Cl^-)和有机酸(柠檬酸)成为了树脂吸附含氮组分的制约因素。用电渗析法脱除无机盐后,阳离子交换树脂对含氮组分的吸附效果显著改善,处理量升高到35倍柱体积;继续用阴离子交换树脂吸附阳离子树脂流出液中的有机酸,即可获得高纯度的大豆低聚糖。同时通过拟合Thomas方程,分别计算了阳离子交换树脂吸附含氮组分和阴离子交换树脂吸附柠檬酸的最大固相吸附浓度。

Soy molasses supernatant mainly consists of soy oligosaccharides （sucrose, raffinose and stachyose） and other impurities such as chromogenic substances, inorganic salts, nitrogen-containing components and organic acids.This paper studied the mechanism of removing impurities from decolorized soy molasses supernatant by ion-exchange resins, and optimized the process.The results showed that the main nitrogen-containing components were five kinds of free amino acids （Aspartic acid, Glutamic acid, Asparagine, Alanine and Tyrosine） and one kind of dipeptide （Glu-Tyr）.Adoption of decolorized supernatant by ion-exchange resins showed low efficient since the handling capacity was about just 3 times of column volume when the effluent broke through. However, ion-exchange resins performed very well on adsorbing nitrogen-135containing components from pure solution with handling capacity of 40 times of column volume. Therefore, it was reasonable to consider that the limiting factors of adsorption were inorganic salts （Na＋, K＋and Cl-） and organic acid （Citric acid）. After desalination by electrodialysis, handling capacity for adsorption of nitrogen-containing components by anion resin rose to about 35 times of column volume.And then high-purity soy oligosaccharides could be got by removing organic acid using anion resin from effluent of cation resin column Besides, the maximum solid phase concentration for nitrogen-containing components and citric acid was respectively calculated by fitting Thomas model.