部分水解瓜尔豆胶的制备、结构鉴定及热力学分析

Preparation, Structure Identification and Thermodynamic Analysis of Partially Hydrolyzed Guar Gum

摘要:

采用可控酶解技术制备不同相对分子质量的部分水解瓜尔豆胶（PHGG），通过离子色谱法计算PHGG中半乳甘露聚糖质量分数。采用红外光谱、核磁共振及X射线衍射表征PHGG的分子结构，采用差示扫描量热法和热重分析法考察PHGG的热力学性质。结果表明，影响PHGG酶解的关键因素为底物质量浓度、酶添加量和酶解时间，通过调控以上因素，制备了中高相对分子质量PHGG（摩尔质量8.92×10⁵ g/mol）、中相对分子质量PHGG（摩尔质量5.07×10⁵ g/mol）和低相对分子质量PHGG（摩尔质量0.62×10⁵ g/mol）。其中，中相对分子质量醇沉PHGG的半乳甘露聚糖质量分数达84.09%。不同相对分子质量PHGG的甘露糖与半乳糖的质量分数比值均降低，主要化学结构未发生改变，晶体区结构有轻微破坏，表明PHGG在较高温度下仍表现出良好的热稳定性。综上，经可控酶解制备的不同相对分子质量PHGG在热加工食品中有良好的稳定性，为瓜尔豆胶应用拓展提供了理论依据。

Abstract:

Partially hydrolyzed guar gum (PHGG) with different relative molecular mass was prepared using controlled enzymatic hydrolysis technology, and the mass fraction of galactomannan in PHGG was calculated by ion chromatography. The molecular structure of PHGG was characterized by infrared spectroscopy, nuclear magnetic resonance and X-ray diffraction. Thermodynamic properties of PHGG were investigated by differential scanning calorimetry and thermogravimetric analysis. The results showed that the critical factors influencing the enzymatic hydrolysis of PHGG were substrate mass concentration, enzyme addition amount, and enzymatic hydrolysis time. By manipulating these factors, medium and high relative molecular mass PHGG (molar mass 8.92×10⁵ g/mol), medium relative molecular mass PHGG (molar mass 5.07×10⁵ g/mol) and low relative molecular mass PHGG (molar mass 0.62×10⁵ g/mol) were prepared. Among them, the mass fraction of galactomannan in medium relative molecular mass alcohol-precipitated PHGG reached 84.09%. In PHGG with different relative molecular mass, the mass fraction ratio of mannose to galactose decreased, and the main chemical structure remained unchanged, but there were minor disruptions to the crystalline region structure, indicating that PHGG exhibited good thermal stability even at elevated temperatures. Overall, PHGG with different relative molecular mass, prepared by controlled enzymatic hydrolysis, has good stability in thermally processed foods, which provides a theoretical basis for the application of guar gum.