影响半纤维素发酵液中分离纯化木糖醇关键因子的研究

Effects of Several Key Factors on Xylitol Separation and Purification in Fermented Hemicellulose Hydrolyzates

为了优化半纤维素发酵液中木糖醇的结晶工艺,以木糖醇溶液与半纤维素发酵液为研究对象,考察了木糖醇初始浓度、残糖(阿拉伯糖)、晶种和结晶温度对木糖醇结晶动力学的影响,并确定了木糖醇初始质量浓度为750g/L,结晶温度为-4℃。在木糖醇溶液中添加1‰木糖醇晶种,能缩短结晶诱导期的延续时间,提高结晶速度。木糖醇溶液中少量的阿拉伯糖能提高木糖醇结晶速度,但当阿拉伯糖质量浓度高于120g/L时,木糖醇晶体的纯度会降低。以木糖醇溶液为底物结晶木糖醇,与半纤维素发酵液相比,两者的结晶动力学曲线较吻合,为进一步优化木糖醇结晶工艺提供了依据。

In order to optimize the xylitol crystallization technology for the fermented hemicellulose hydrolyzates, two sets of crystallization tests were performed on both xylitul solutions and fermented hemieellulose hydrolyzates. The influences of xylitul concentration, remained sugar （arabinose） , temperature and crystal seeds on the kinetics of xylitol crystallization were investigated. The optimum initial xylitul concentration of crystallization media was about 750 g/L, and the optimum crystallization temperature was -4 ℃. By adding 1‰ xylitol crystal seeds, crystallization time was shortened, and improved crystallization rate was obtained. The arabinose present could increase the xylitul crystallization rate, however, the xylitol crystal purity deteriorated when the arabinose concentration exceeded 120 g/L. Xylitol solutions composed of arabinose were used for xylitol crystallization. The kinetic curve of xylitol crystallization in xylitel solutions was in good agreement with that in the fermented hemicellulose hydrolyzates. The results can greatly facilitate further study on the kinetics of xylitol crystallization in fermented hemieellulose hydrolyzates.