文献类型：期刊文献

英文题名：Purification of DP 6 to 8 chitooligosaccharides by nanofiltration from the prepared chitooligosaccharides syrup

作者：Dong, Huizhong[1,2]; Wang, Yaosong[1,2]; Zhao, Liming[1,2]; Zhou, Jiachun[1,2]; Xia, Quanming[1,2]; Jiang, Lihua[1,2]; Fan, Liqiang[1,2]

机构：[1] State Key Laboratory of Bioreactor Engineering, R&D Center of Separation and Extraction Technology in Fermentation Industry, East China University of Science and Technology, Shanghai, 200237, China; [2] Shanghai Collaborative Innovation Center for Biomanufacturing Technology, Shanghai, 200237, China

年份：2014

卷号：1

期号：1

外文期刊名：Bioresources and Bioprocessing

收录：EI(收录号：20224513078403)

语种：英文

外文关键词：Desorption - Hydrogen bonds - Mass spectrometry - Polymerization - Purification

摘要：Background: Chitooligosaccharides (COS) with degrees of polymerization (DP) 6 to 8 are degraded from chitosan, which possess excellent bioactivities. However, technologies that could purify them from hydrolysis mixtures in the narrow DP range (984 to 1,306 Da) are absent. The objective of this research is to purify DP 6 to 8 COS by nanofiltration on the basis of appropriate adjustments of the feed condition. Methods: Syrup containing DP 6 to 8 COS at different concentrations (19.0 to 46.7 g/L) was prepared. A commercial membrane (QY-5-NF-1812) negatively charged was applied. Experiments were carried out in full recycle mode, so that the observed COS retentions were investigated at various transmembrane pressures (6.0 to 20.0 bar), temperatures (10°C to 50°C), and pHs (5.0 to 9.0). Then, the feasibility of separation of DP 6 to 8 COS was further studied by concentration ratio under optimum conditions. Results: The results indicate that the purification of DP 6 to 8 COS by nanofiltration NF is feasible. It was found that the permeate flux was 95.0 L/(m2 h) at 10.0 bar, while it reached to 140.0 L/(m2 h) at 20.0 bar, and it increased with feed temperature, but the membrane pores were also swelled by heating and led to an irreversible wastage of target oligomers. Additionally, the retention behaviors of chitooligosaccharides are significantly influenced by pH. Conclusions: Although glucosamine and dimer were permeatable at low pH, their retention ratios were remarkably varied from 0.458 to 0.864 when pH was 9.0. With the interaction of hydrogen bonds, structural curling and overlapping of chitooligosaccharides were formed. Consequently, the rejection of chitooligosaccharides at various pHs is variable. Spray-dried products were finally characterized by the matrix-assisted laser desorption/ionization time-of-flight mass spectrum. The spectrum identified the distributions of hexamer, heptamer, and octamer. Combined with high-performance liquid chromatography profiles, the purity and yield of DP 6 to 8 chitooligosaccharides were up to 82.2% and 73.9%, respectively. ? 2014 Dong et al.