酶法制备低甲氧基果胶的工艺研究

以新鲜橙皮为原料,在盐酸水解乙醇沉淀提取果胶之前,激活并利用果皮中固有的果胶酯酶进行果胶的酶法脱酯,制备低甲氧基果胶,以产品的甲氧基含量和果胶得率为指标,确定最佳工艺条件。结果表明,新鲜橙皮内源酶法制备低甲氧基果胶的最佳工艺条件为:加入果皮浆液量0.15%的内源性果胶酯酶激活剂碳酸钠,控制温度45℃,pH8.0进行脱酯,时间60min;果胶提取温度90℃,时间60min,pH2.0。在此条件下制备的果胶甲氧基含量为5.93%,符合低甲氧基果胶标准,果胶得率为2.46%。     

利用果胶酯酶制备低酯果胶工艺研究

研究高酯果胶脱酯工艺的最佳条件;利用果胶酯酶对商品高酯果胶进行脱酯,采用L934正交试验法研究确定酶用量、脱酯温度、pH及脱酯时间对脱酯效果的影响.利用果胶酯酶进行脱酯的最佳工艺参数为:果胶酯酶0.06 g,脱酯温度45℃,脱酯pH 7,脱酯时间70 min,所得果胶甲氧基含量为4.96%.利用酶法制备低酯果工艺简单,脱酯效率较高.     

碱催化脱酯制取低甲氧基果胶的研究

以商品高酯果胶为原料,以脱酯率、产品粘度、得率为指标,对碱性条件下影响低甲氧基果胶制备的因素进行正交试验以获得制取低甲氧基果胶的最佳工艺。试验结果表明最佳工艺条件为:以浓度2%的高甲氧基果胶为原料,控制温度0℃和pH值9.0,搅拌反应45min进行脱酯;再在常温下利用pH为3.0的60%乙醇溶液搅拌5min以析出果胶。所得产品酯化度(DE)为42.56%、粘度116.2MPa·s、半乳糖醛酸含量(AGA)75.4%;果胶得率89.67%,各项指标符合低甲氧基果胶产品标准。     

从柚皮中提取低甲氧基果胶的工艺研究

目的 研究从柚皮中提取低甲氧基果胶的最佳工艺条件.方法 采用酸解法浸提并用碱法脱酯提取低甲氧基果胶,通过单因素试验和正交试验优化工艺条件.结果 各因素对提取低甲氧基果胶的影响顺序为:提取液pH>提取时间>提取温度>液料比.最佳提取条件为液料比(mL/g)21:1,提取液pH 2.0,提取温度80℃,提取时间70 min.结论 在此工艺条件下果胶得率5.51%,所得果胶的甲氧基含量6.33%,符合国家规定标准.     

酶法制备低甲氧基果胶的工艺优化研究

以酸橙皮渣为原料,在酸法提取果胶的基础上,向果胶提取液中加入外源性果胶酯酶,制备低甲氧基果胶.通过单因素试验和Box-Behnken设计以及响应面分析确定酶法制备低甲氧基果胶的最佳工艺参数为加入经1 000倍稀释的果胶酯酶5.39 mL、反应50 min、42.71 ℃、pH 4.61,在此条件下果胶酯化度由67.83%降低至42.55%.     

微波辅助制备西瓜皮低酯果胶工艺研究

以西瓜皮为原料,利用微波辅助提取西瓜皮果胶,直接制备西瓜皮低酯果胶.在单因素实验的基础上,利用正交实验对微波辅助制备低酯果胶的工艺进行了研究.结果表明,微波辅助制备西瓜皮低酯果胶的工艺最佳条倬为:料液比1:40,处理时间3min,提取液pH 1.0,微波功率510W,脱酯pH12.0,脱酯时间40min,脱酯温度20℃.在此条件下西瓜皮低酯果胶提取率为3.16%,甲氧基含量5.14%.     

从柚皮中提取低甲氧基果胶的工艺研究

目的 研究从柚皮中提取低甲氧基果胶的最佳工艺条件.方法 采用酸解法浸提并用碱法脱酯提取低甲氧基果胶,通过单因素试验和正交试验优化工艺条件.结果 各因素对提取低甲氧基果胶的影响顺序为:提取液pH>提取时间>提取温度>液料比.最佳提取条件为液料比(mL/g)21:1,提取液pH 2.0,提取温度80℃,提取时间70 min.结论 在此工艺条件下果胶得率5.51%,所得果胶的甲氧基含量6.33%,符合国家规定标准.     

复合磷酸盐法预处理西瓜皮制备低酯果胶工艺优化

以西瓜皮为原料,研究复合磷酸盐法预处理西瓜皮制备低酯果胶的工艺条件。实验结果表明从西瓜皮中提取低酯果胶的最佳条件：质量分数2% 的磷酸钠、质量分数0.9% 的磷酸氢二钠、质量分数0.3% 的焦磷酸钠、质量分数0.6% 的六偏磷酸钠配比的复合磷酸盐预处理,脱酯pH10、脱酯温度15℃、脱酯时间0.5h。在此条件下,低酯果胶得率5.07%,甲氧基含量4.49%,脱酯效果较好。     

火龙果皮中果胶的提取及其结构研究

进行火龙果皮中果胶提取工艺研究,并对优选工艺下提取的果胶进行结构研究。实验结果得出果胶优选提取工艺为料液比1∶7,提取液pH为2.0,提取温度90℃,提取时间90min。在该提取工艺条件下果胶提取率为91.58%,果胶得率为2.34%,果胶提取较充分。果胶甲氧基含量为4.836%,酯化度为29.57%,属于低酯果胶;果胶重均分子量87166,数均分子量59137,为分子量相对较小的果胶。     

微波法萃取橘皮中果胶的研究

以橘皮为原料在微波条件下提取果胶进行了研究，探讨盐析pH值、微波加热时间、硫酸铝用量、液料比、盐析温度、盐析时间等因素对果胶产率的影响，结果表明：微波法提取果胶的最佳工艺条件为盐析pH5．0，微波力加热时间5min，硫酸铝用量2．5g，液料比16mL／g，盐析温度60％，盐析时间60min，果胶平均得率25％。     

Influence of pectin properties and processing conditions on thermal pectin degradation

Texture degradation of fruits and vegetables during thermal processing is partly due to pectin depolymerization. In this contribution we investigate the influence of pectin properties (degree and pattern of methoxylation) and processing conditions (pH 2.0, 3.0, 5.0 and 7.0; temperatures of 80 up to 110 °C) on pectin degradation rate constants. Pectins with different degrees and patterns of methoxylation were prepared and heated, the extent of acid hydrolysis, β-elimination and demethoxylation was assayed as a function of treatment time. As the degree of methoxylation and pH decreased, β-elimination rate constants decreased while acid hydrolysis rate constants increased. Demethoxylation rate constants were minimal at pH 3.0 and increased both at lower and higher pH. Reaction rate constants were not considerably influenced by the pattern of methoxylation. All reaction rate constants increased with increasing temperature. As β-elimination rates are reduced by competing demethoxylation, both rate constants were compared. The ratio of these reaction rate constants showed no trend with pH. However, an increase in degree of methoxylation or temperature resulted in a more pronounced increase in β-elimination rate constants than in demethoxylation rate constants.     

Improving pectin technology.

The effect of ultrasonic treatment on pectin stability in aqueous solution was studied to establish conditions which minimized degradation. Pectin was extracted under these conditions with an increased yield and without reducing the drainage properties of the extracted fruit mass. A pulsed ultrasonic method in aqueous acidic medium was developed, successfully tested with three different apple pomace samples, and its advantages demonstrated.     

南瓜果胶脱色工艺的研究

将南瓜皮中提取的果胶分别用活性炭、双氧水及树脂进行脱色研究。实验结果表明,树脂201×7采用摆幅为5r/min,在经过15h振荡后效果最佳。     

Inhibition of tomato pectin methylesterase by partially purified kiwi pectin methylesterase inhibitor protein

The inhibition of tomato pectin methylesterase (PME) by a recently discovered kiwi pectin methylesterase inhibitor (PMEI) is described. PME was consequently purified by CM Sephadex C-50, Concanavalin A-Sepharose 4 B and Mono S chromatography, and PMEI by Q-Sepharose and Sephacryl S-200 chromatography. Inhibition of tomato PME activity under optimal conditions (0.125 m NaCl, pH 7.5) by partially purified kiwi PMEI (MW of 27 kD, pI ≥ 3.67) was independent of the PMEI/PME ratio between 36 and 61% of the maximal uninhibited activity. the non-competitive inhibition observed was optimal in the pH range of 5 to 7. PMEI was inactivated by heating to 120°C, and showed actinidin-like activity towards N-α-benzyloxycarbonyl-L-lysine p -nitrophenyl ester (CBZ-lys-ONp) and azocasein which was partially inhibited by the protease inhibitor leupeptin.     

Microwave-assisted extraction of lime pectin

Pectin was extracted from lime flavedo, albedo and pulp by employing microwave-assisted extraction (MAE) under pressure. Heating times ranged from 1 to 10 min. Optimal time of heating was 3 min. Molar mass, viscosity, radius of gyration and hydrated radius were found to decrease with heating time. At 3 min heating time, depending on the lime fraction which was extracted, weight average molar mass ranged from about 310,000 to 515,000 Da, and weight average intrinsic viscosities ranged from about 9.5 to 13 dL/g. Pectins dissolved in 0.05 sodium nitrate were characterized by HPSEC with online light scattering, dynamic light scattering and viscosity detection. Molar mass polydispersity passed through maximum at 4 min. Molecules of pectin became less compact with increasing heating time. The results obtained here are consistent with previous evidence that extracted pectins may exist in solution as networks, partially formed networks, i.e. branched molecules or linear molecules depending on extraction conditions and the solvent in which they are dissolved.     

桑皮胶质绿色降解法

对桑皮胶质绿色降解方法进行探讨,分析了温度、时间、pH值、接种量等条件与残胶率的关系。通过正交试验,确定其最佳工艺条件为:温度37℃,时间22 h,pH值7.3,接种量12.5%,此时残胶率为13.4%。对胶质降解后的桑皮纤维进行长度、细度、断裂强度性能测试,其长度为35~45 mm,细度为3.6~4.0 tex,断裂强度为3.71~5.07 cN/dtex。     

Interaction of lysine with pectin

The interaction of l-lysine with citrus pectin was studied in a model system to determine under what conditions it would occur and whether it would be of physiological significance. Thirty-nine per cent of the lysine was non-diffusible at pH 7, when the pectin concentration was 0·5% and the lysine concentration was $\text{2 × 10}{}^{\mathrm{?3}}\text{M}$. Of this, 29% was restricted due to the Donnan effect and the remainder was specifically bound. Increasing the pH (in the range 6–8) and the pectin concentration both increased the non-diffusible lysine. Increasing the ionic strength and the degree of esterification both decreased the non-diffusible lysine. It was concluded that lysine would not bind to pectin in the intestine because of the high salt concentration there.     

果胶类多糖的功能特性与应用研究

果胶类多糖具有抗癌、降血糖、治疗糖尿病、减轻机体疲劳和增强免疫作用等功效,果胶类多糖也可以作为乳化剂稳定油-水界面,并且能够在酸性条件下稳定牛乳蛋白质,还能够抑制脂质的氧化.从医药行业到食品加工业对果胶类多糖功能特性及其应用进行了综述.     

苹果果胶研究进展

苹果(Malus pumila Mill.)是我国北方广泛种植的经济作物。近年来,很多学者从苹果渣中提取分离得到苹果果胶。现代医学和生物学研究表明,苹果果胶具有抗氧化、降血脂、抗菌及抗癌的功效。本文介绍了苹果果胶的结构、组分分级与特性研究,着重阐述了目前国内外对于苹果果胶的提取、分离的最新进展及其生物活性,讨论了目前研究中存在的问题,并对其发展前景进行了展望。