In this study, pectin was extracted from grapefruit peels with hydrochloric acid and precipitated with 95% ethanol solution and 5% tartaric acid. The physical and chemical properties of pectin obtained were analyzed, ...In this study, pectin was extracted from grapefruit peels with hydrochloric acid and precipitated with 95% ethanol solution and 5% tartaric acid. The physical and chemical properties of pectin obtained were analyzed, including color, texture, degree of esterification, and water solubility. The effects of peel to sol- vent ratio, pH of the solvent, extraction temperature and extraction duration on pectin extraction rate were investigated. On the basis of single-factor experiments, an L9 （34） orthogonal experiment was performed to screen the optimal extraction conditions. According to the results, the optimal combination of technical parame- ters was A1B3 C1 D3, i. e. , solid to liquid ratio 1：40 （g： ml）, pH 2.0, extraction duration 70 rain, extraction temperature 90 ℃. The average pectin extraction rate was 68.60% ; the color of pectin extracted under the optimal conditions varied from milky white to light yellow; the degree of esterification of pectin extracts was 65. 71% ; the extracted pectin exhibited good water solubility. Key words Pomelo peel; Pectin extraction; Optimum conditions; Esterification degree; Water solubility展开更多
基金Supported by Project of Education Department of Jiangxi Province(JXJG-08-4-27)
文摘In this study, pectin was extracted from grapefruit peels with hydrochloric acid and precipitated with 95% ethanol solution and 5% tartaric acid. The physical and chemical properties of pectin obtained were analyzed, including color, texture, degree of esterification, and water solubility. The effects of peel to sol- vent ratio, pH of the solvent, extraction temperature and extraction duration on pectin extraction rate were investigated. On the basis of single-factor experiments, an L9 （34） orthogonal experiment was performed to screen the optimal extraction conditions. According to the results, the optimal combination of technical parame- ters was A1B3 C1 D3, i. e. , solid to liquid ratio 1：40 （g： ml）, pH 2.0, extraction duration 70 rain, extraction temperature 90 ℃. The average pectin extraction rate was 68.60% ; the color of pectin extracted under the optimal conditions varied from milky white to light yellow; the degree of esterification of pectin extracts was 65. 71% ; the extracted pectin exhibited good water solubility. Key words Pomelo peel; Pectin extraction; Optimum conditions; Esterification degree; Water solubility
文摘用柚皮纤维原料及其提取物不溶性膳食纤维、果胶结合D12492高脂饲料饲喂C57BL/6小鼠67 d,观察小鼠摄食量、体质量、血脂生化指标、脏器指数及肠道菌群变化,探究膳食纤维预防肥胖及其调节肠道菌群的效果。结果表明:与肥胖对照组(obesity control group,OCG)相比,不溶性膳食纤维组(insoluble dietary fiber group,IDF)小鼠体质量、血清总胆固醇(total cholesterol,TC)及低密度脂蛋白胆固醇(low density lipoprotein cholesterol,LDL-C)浓度、附睾脂肪系数、Lee’s指数分别降低4.9%、8.3%、14.29%、0.44%、2.54%;果胶组(soluble dietary fiber group,SDF)分别降低5.1%、11.4%、21.21%、0.60%、2.47%;原料组(raw material group,RMG)分别升高1.3%、7.4%、12.5%、0.96%、1.27%;而IDF、SDF、RMG小鼠血清高密度脂蛋白胆固醇(high density lipoprotein cholesterol,HDL-C)浓度分别提高0.52%、0.78%、5.44%。补充柚皮膳食纤维提高了小鼠肠道中拟杆菌门、毛螺菌属相对丰度,降低了厚壁菌门、脱硫菌门、脱铁杆菌相对丰度。结论:柚皮不溶性膳食纤维、果胶对预防肥胖和降低血脂有显著效果。其作用效果并非通过抑制摄食量实现,很可能与其增加小鼠肠道中拟杆菌门、毛螺菌属等相对丰度,降低脱硫菌门、脱铁杆菌等相对丰度有关。厚壁菌门相对丰度的升高与体质量变化无显著相关性,但与HDL-C浓度呈显著正相关,与LDL-C浓度呈显著负相关,有利于控制血脂;拟杆菌门相对丰度的升高与体质量及TC、HDL-C浓度呈显著负相关,与LDL-C浓度呈显著正相关,有利于控制体质量,但不利于控制血脂,因此拟杆菌门与厚壁菌门对体质量和血脂的影响还需要深入研究。未经提取纯化的柚皮纤维能增加小鼠摄食量,使其体质量和LDL-C浓度增加,但同时能显著增加HDL-C浓度,因此其对体质量和血脂影响的利弊还需要进一步确认。
