复合酶解法提取的咖啡果皮多糖的结构表征及其生物有效性研究

Structural Characterization and Bioavailability Evaluation of Polysaccharides Extracted from Coffee Peels by Composite Enzymatic Hydrolysis

摘要:

【目的】优化咖啡果皮多糖的提取工艺并探究其结构和生物有效性。【方法】 采用复合酶解法提取咖啡果皮多糖，通过红外分析、单糖组成测定、相对分子质量测定和糖苷键连接方式分析等对其结构进行表征，并分析其生物有 效性。【结果】 咖啡果皮多糖最佳提取工艺条件为：纤维素酶质量分数2.6%、碱性蛋白酶质量分数2.6%、木瓜蛋白酶质量分数2.6%、果胶酶质量分数3.8%、提取温度60 ℃、提取时间1.5 h、料液比1 g∶100 mL、pH 4。复合酶解法可有效维持咖啡果皮多糖的生物有效性。结构表征结果显示，咖啡果皮多糖重均分子量为1 626 765，含鼠李糖、阿拉伯糖、半乳糖、葡萄糖、半乳糖醛酸，摩尔比为4.39∶23.75∶28.03∶7.58∶36.25，该多糖以α-构型吡喃糖为骨架，含有→3）-Galp-（1→、→4）-Galp-（1→等糖苷键，其中的主要组成（半乳糖醛酸）以→4）-Galp-UA-（1→形式存在，为该酸性多糖的特征性结构。【结论】 该研究可为咖啡副产物咖啡果皮的开发利用提供理论参考。

Abstract:

[Objective] This study aims to optimize the extraction process of polysaccharides from coffee peels and explore their structure and bioavailability. [Method] The composite enzymatic hydrolysis method was employed to extract polysaccharides from coffee peels. The polysaccharide structure was characterized from aspects such as infrared analysis, monosaccharide composition, molecular weight determination, and glycosidic linkage analysis. The bioavailability of the extracted polysaccharides was analyzed. [Result] The extraction process conditions were optimized as follows: a cellulase mass fraction of 2.6%, an alkaline protease mass fraction of 2.6%, a papain mass fraction of 2.6%, a pectinase mass fraction of 3.8%, an extraction temperature of 60 ℃, extraction time of 1.5 h, a solid-to-liquid ratio of 1 g∶100 mL, and pH 4. The composite enzymatic hydrolysis method effectively maintained the bioavailability of the polysaccharides. Structural characterization revealed that the coffee peel polysaccharides had a weight-average molecular weight of 1 626 765 and were composed of rhamnose, arabinose, galactose, glucose and galacturonic acid at a molar ratio of 4.39∶23.75∶28.03∶7.58∶36.25. It adopted an α-pyranose backbone and contained typical glycosidic linkages including →3)-Galp-(1→ and →4)-Galp-(1→. Galacturonic acid, as the major constituent, existed in the form of →4)-Galp-UA-(1→, which constituted the characteristic structural motif of the acidic polysaccharide. [Conclusion] This study provides a scientific reference for the in-depth research and development of coffee peels, a coffee by-product.