The aim of this study was to evaluate the effects of alcohol-acid degradation on the structural and physicochemical characteristics of guar gum. Guar gum (50 wt.%) was treated with methanol, ethanol, 2-propanol, or 1-butanol containing 1 or 2 mL 36% hydrochloric acid at 75 °C for 30–240 min. The linear relationship between 1/Mw and time suggested that alcohol-acid degradation followed first-order kinetics with rate constants varying directly with the number of alcohol carbon atoms and acid concentration. Alcohol-acid treatment exerted no effect on the chemical and crystal structure of guar but significantly decreased shear viscosity, slightly increased solubility, mildly reduced thermostability, and dramatically darkened colour. This study extended the knowledge of the effect of alcohol on the acid hydrolysis of guar and will contribute to the development of a large-scale procedure for guar gum degradation.

中文翻译：

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酒精-酸处理瓜尔胶的结构和物理化学变化

这项研究的目的是评估乙醇酸降解对瓜尔豆胶结构和理化特性的影响。瓜耳胶（50 wt。％）在75°C下用含有1或2 mL 36％盐酸的甲醇，乙醇，2-丙醇或1-丁醇处理30–240分钟。1 / Mw和时间之间的线性关系表明，醇-酸降解遵循一级动力学，速率常数直接随醇碳原子数和酸浓度而变化。酒精-酸处理对瓜尔胶的化学和晶体结构没有影响，但剪切粘度显着降低，溶解度略有增加，热稳定性略有降低，并且颜色显着变深。