三聚甘油脂肪酸酯对甘油二酯结晶特性的影响

Effect of Polyglycerol Fatty Acid Esters on Crystallization behaviors of Diacylglycerol

摘要:

甘油二酯（Diacylglycerol, DAG）是一种功能性油脂，可作为潜在的食品专用油脂，故对其结晶特性的研究具有重要的理论意义。在鼓泡式反应器无溶剂体系中，利用脂肪酶Lipozyme 435催化硬脂酸、油酸与甘油酯化反应制备甘油二酯。酯化产物经分子蒸馏纯化得到含量为78.39 wt%的甘油二酯。利用差示扫描量热仪、脉冲核磁共振仪、X射线衍射仪和偏光显微镜考察两种三聚甘油脂肪酸酯（Polyglycerol fatty acid ester, PGFE）对甘油二酯结晶特性的影响。结果表明，硬脂酸三聚甘油酯（PGFE1）对甘油二酯具有促进结晶作用；亚油酸三聚甘油酯（PGFE2）对甘油二酯具有抑制结晶作用，当PGFE2的含量由2%增加为10%时，其抑制作用变大。X射线衍射结果显示PGFE1对甘油二酯β′型晶型有稳定作用。偏光显微镜观察到PGFE1的添加使甘油二酯的晶体变得更为细腻。

Abstract:

Diacylglycerol (DAG) is a functional lipid that can potentially be used for food applications, and therefore, the study of its crystallization behaviors is of great theoretical significance. In this study, DAG was prepared through lipozyme 435-catalyzed esterification of stearic acid, oleic acid, and glycerol in a solvent-free system using a bubble column reactor. After the purification by molecular distillation, 78.39 % (wt.) DAG was obtained from the esterification product. The effects of two types of polyglycerol fatty acid esters (PGFEs) on the crystallization behaviors of DAG were investigated by differential scanning calorimetry, pulsed nuclear magnetic resonance, X-ray diffraction, and polarized light microscopy. The results showed that polyglycerol stearic acid ester (PGFE1) promoted the crystallization of DAG, while polyglycerol linoleic acid ester (PGFE2) inhibited the crystallization of DAG, and this inhibitory effect was enhanced when the PGFE2 content was increased from 2% to 10%. The results of X-ray diffraction indicated that the presence of PGFE1 stabilized the DAG in β'-crystal form. Finally, the polarized light microscopy revealed that the addition of PGFE1 made the crystal of DAG more delicate.