豆腐柴叶果胶理化性质及“神仙豆腐”制备的条件

摘要

Objective: To explore the sugar composition of pectin extracted from Premna microphylla leaves and its effect on the coagulation of Fairy Tofu,a jelly-like food prepared from Premna microphylla leaves and coagulant.Methods: Pectin was obtained as a creamy yellowish precipitate from Premna microphylla leaf juice by sulfuric acid hydrolysis,ethanol precipitation,TCA-chloroform deproteinization,ammonia-ethanol decolorization and 95% ethanol precipitation.After further hydrolysis with sulfuric acid,the precipitate(pectin) was analyzed by silica gel G thin-layer chromatography for saccharide composition.In addition,its pH,soluble pectin content and degree of esterification were determined and its protein content was measured by biuret protein assay.Also,we analyzed the effects of coagulant type(synthetic coagulant and plant ash) and dosage on the coagulation of the pectin for Fairy Tofu production.Results: The pectin extract contained 78.24% saccharides,mainly glucose,fructose and D-mannose and 21.76% protein.It had high water binding capacity and a degree of esterification of 74.6% and its properties were close to international quality standards.The Fairy Tofu prepared from it revealed a degree of coagulation higher than 100.Conclusion: The preparation of Fairy Tofu from Premna microphylla leaves is based on the simultaneous interactions of pectin with calcium and magnesium ions.%目的：研究豆腐柴叶果胶的成分及理化性质,并揭示其制备豆腐的机制。方法：采用硫酸对豆腐柴叶汁水解,乙醇沉淀分离,三氯醋酸-氯仿合剂去蛋白,氨化乙醇脱色,95%乙醇沉淀纯化,获乳黄色沉淀物;该沉淀物采用硫酸水解,硅胶G薄板层析测定多糖种类与组成;测定果胶pH值、可溶性果胶含量和酯化度;双缩脲比色法测定果胶蛋白质含量;与民间制＂神仙豆腐＂同类方法验证提取物制豆腐效果。结果：豆腐柴叶果胶的主要成分是葡萄糖、果糖、D-甘露糖,3种糖含量为78.24%,蛋白含量为21.76%;果胶吸水性强,其性质与国际检测标准相近,酯化度为74.6%,果胶制成的豆腐凝集度〉100。结论：豆腐柴叶制备豆腐是果胶与钙、镁离子的共同作用结果。