脱乙酰基对魔芋葡甘聚糖羧甲基改性的影响及产物结构表征  

Effect of Deacetylation in Course of Konjac Glucomannan Carboxy Methylation and Structure Characterization of the Products

作　　者：汪超[1] 李斌[1] 谢笔钧[1] 

机构地区：[1]华中农业大学食品科技学院天然产物研究室

出　　处：《中国农业科学》2005年第10期2090-2095,共6页Scientia Agricultura Sinica

基　　金：国家"863计划"(2002AA2Z4181)

摘　　要：魔芋葡甘聚糖(KGM)链上连有乙酰基团,KGM与碱反应脱乙酰基发生分子链的缔合作用。针对脱乙酰基的这种影响进行羧甲基化方法的改进,在乙醇介质中先混合醚化剂,再进行碱化催化反应制备羧甲基魔芋葡甘聚糖(CMK),并通过与传统的先碱化再醚化的KGM羧甲基改性方法比较,达到乙酰基脱出顺序上的不同。以取代度(DS)和表观粘度(η)来确定改进羧甲基化的条件。结果表明,70℃、pH12反应3.0h,产物可获得0.5278的DS,而在55℃、pH9反应2.0h产物η可高达15.57Pa·s,其溶胀速率较优。运用红外光谱、广角X-射线衍射和示差扫描量热法表征产物结构并探讨脱乙酰基对KGM羧甲基改性的影响。The acetyl groups are attached to konjac glucomannan （KGM）, deacetyltion occurs on alkaline treatment and causes the association of molecular chains. The improved method of konjac glucomannan （KGM） carboxy methylation was proposed in this paper according to the effects of deacetylation. Carboxymethyl KGM （CMK） were synthesized by blending KGM with etherification agent first and then basifying and catalyzing in ethanol. Basifying first and then etherifying prepared traditional carboxymethyl KGM （TCMK）. Using both degree of substitution （DS） and apparent viscosity （η） as evaluation indexes, the reaction conditions were determined. The contrast of two modification methods show different sequence of deacetyltion and the results indicate that the CMK has better value of DS=0.5278 （70℃, pH 12 for 3 hours） and η=15.57 Pa·s （55 ℃, pH 9 for 2 hours） and excellent hydrated rate. The structure of products was characterized by means of infrared spectra, wide-angle X-ray diffraction and differential scanning caloriimetry and the effect of deacetylation in course of konjac glucomannan carboxy methylation was analyzed.

关 键 词：魔芋葡甘聚糖 脱乙酰基 羧甲基化 结构表征 产物结构 改性方法 示差扫描量热法 催化反应 X-射线衍射 KGM 

分 类 号：O631[理学—高分子化学]