亲水色谱法测定甜叶菊叶片中糖苷含量

建立测定甜叶菊叶片中三种主要糖苷成分:蛇菊苷、莱鲍迪苷C以及莱鲍迪苷A的高效液相色谱方法.选用70％(g/g)的乙醇/水溶液为萃取溶剂,超声法提取甜叶菊叶片中的糖苷成分,步骤简单灵活.液相色谱分析条件建在亲水原理基础上,采用ZORBAX-NH2柱,乙腈、水为流动相梯度洗脱,外标法定量.该方法分离度和线性良好,三种组分回收率在90％以上,能满足不同品种甜叶菊叶片糖苷含量的测定.利用该方法对5种甜叶菊样品进行了分析,结果准确,重复性好,是一种可信的方法.     

HPLC法快速测定甜叶菊中瑞鲍迪苷A

建立以甜叶菊叶片为原料,采用超声萃取法用体积浓度70%的乙醇对瑞鲍迪苷A进行提取,使用高效液相色谱仪检测甜叶菊样品液中瑞鲍迪苷A含量的方法。采用-NH2基柱(250 mm×4.6 mm,5μm),流动相为乙腈与水体积比80∶20,流速1.2 m L/min,紫外检测波长210 nm,进样量15μL。甜叶菊中瑞鲍迪苷A分别在纯水、体积浓度70%乙醇、80%乙腈中提取得率为10.25 mg/g、11.52 mg/g、13.49 mg/g,范围内线性关系良好相关系数R2=0.999 9。采用体积浓度70%乙醇对瑞鲍迪苷A进行提取,此方法安全有效、操作简单、定量准确。     

壳聚糖澄清甜叶菊水提液及其澄清机理探讨

研究壳聚糖絮凝剂在甜叶菊提取液澄清过程中的作用。分别以甜叶菊水提液的澄清率和甜菊苷的损失率为指标,考察不同因素对絮凝效果的影响。通过正交试验法确定壳聚糖絮凝的较优工艺条件为：1%壳聚糖溶液投加量2mL/g甜叶菊干叶、甜叶菊提取液质量浓度1g生药/10mL提取液、pH6.0、温度45℃,絮凝时间4h。在该条件下,甜叶菊水提液的澄清率为86.63%,甜菊苷的损失率为6.89%,与膜分离法澄清的效果相近,且无需特殊设备。与传统化学絮凝法相比,壳聚糖絮凝法能更有效地保留水提液中的有效成分,具有絮凝效果好、易生物降解、对环境安全、无二次污染等优点。     

超声波法提取甜叶菊甙的工艺技术研究

以甜叶菊干叶为原料,研究超声波法提取甜叶菊甙的最佳工艺。采用单因素试验,考察超声时间、料液比、超声频率、提取次数和超声温度5个技术参数对超声波法提取甜叶菊甙效果的影响,采用正交试验进行技术参数优化。试验结果表明,在超声时间50min、超声频率70kHz、料液比1∶50、提取次数2次、超声温度60℃时甜叶菊甙提取效果最好,甜叶菊甙的提取率可达到82%,提取时间为水浸提法的1/10。     

离子交换法提取木瓜皮中果胶的动力学研究

以木瓜皮为原料,分别研究了离子交换树脂法和酸提法提取果胶的动力学模型,获得速率常数和表观活化能,经过有效性检验和模型预测能力验证,模型均能很好预测果胶提取的动力学过程。离子交换法提取果胶的活化能Ea为23.68kJ/mol,与酸提法获得的37.88kJ/mol相比明显降低,离子交换树脂法提取木瓜皮中果胶明显优于酸提法。在树脂用量为5%、料液比为1∶30(g/mL)、浸提液pH值为1.5条件下,离子交换树脂法提取木瓜皮中果胶的最佳浸提温度为80℃,动力学分析优化最佳结果,得T_max=117.3min,果胶得率达17.47%,与试验结果相吻合。     

超高压辅助提取甜叶菊中瑞鲍迪苷A工艺及其机理分析的研究

通过超高压辅助提取甜叶菊中瑞鲍迪苷A工艺的寻优试验,以瑞鲍迪苷A得率为响应值,考查液料比、提取压力和保压时间三个因素对瑞鲍迪苷A得率的影响。试验结果表明,在16.8∶1mL/g液料比、429.5MPa提取压力和7.7min的保压时间下,瑞鲍迪苷A的得率达到35.2mg/g。超高压辅助提取改变了甜叶菊粉内部的微组织结构,表面的孔隙变得更大更多,组织结构变得更加疏松,从而强化了瑞鲍迪苷A的润湿、溶解和扩散的传质过程。     

离子交换纤维脱色预处理对HP-20吸附树脂吸附甜菊糖苷的影响

研究了离子交换纤维脱色预处理对HP-20吸附甜菊糖苷的影响.结果表明:离子交换纤维可显著脱除甜叶菊提取液中的色素,色素脱出率达89.59%,但对甜菊糖苷基本无吸附.在HP-20吸附树脂前增加CL型离子交换纤维对减轻后工序HP-20吸附树脂负荷,提高产品质量有较大帮助.HP-20吸附树脂可用85%乙醇溶液替代甲醇作为洗脱剂,用95%乙醇氢氧化钠溶液进行再生以保持吸附树脂的吸附效能.     

玫瑰茄花色苷纯化过程中有机酸的回收及其性质研究

为提高玫瑰茄花萼色素产品的附加值,促进玫瑰茄在食品添加剂方面的利用,该文从大孔树脂纯化玫瑰茄花色苷过程中分离回收有机酸,并对其性质进行研究.利用超声辅助提取法提取玫瑰茄花色苷,在AB-8大孔树脂纯化花色苷的过程中采用阴离子-阳离子交换柱联合法回收有机酸流出液,并测定树脂吸附效能.经扫描电镜观察有机酸粉末发现,样品大多数...     

南瓜果胶不同提取方法的研究

以南瓜果肉为材料,采用咔唑比色的方法,通过正交试验,分别研究超声波法、纤维素酶法和离子交换树脂法提取南瓜果胶的最佳提取条件。结果表明：超声波法的最佳提取工艺条件为：超声波功率400W,时间35min,液料比10:1(ml/g),果胶得率5.98%;纤维素酶法提取果胶的最佳工艺条件为：酶解时间2.0h,pH4.5,酶解温度55℃,加酶量0.5%,果胶得率9.56%;离子交换树脂法提取果胶的最佳工艺条件为：树脂用量15%,料液比为1:20(g/ml),pH2.5,时间2.0h,温度80℃,果胶得率7.62%。三种提取方法进行比较,纤维素酶法果胶得率最高,为南瓜果胶的最佳提取工艺。     

解郁胶囊中甘草提取纯化工艺研究

目的优选解郁胶囊中甘草的最佳提取、纯化工艺条件。方法采用高效液相色谱法测定甘草苷、甘草酸含量,以乙醇体积分数、乙醇用量、提取时间为考察因素,以甘草苷、甘草酸提取率和浸膏得率的综合评分为指标,采用正交试验法优选甘草提取工艺;以比吸附量和洗脱率为指标,采用大孔吸附树脂法纯化。结果优选提取工艺条件为50%乙醇,10倍量,提取2次,每次2 h;纯化工艺条件为选用D101型大孔吸附树脂,上样溶液质量浓度为0.2 g/m L,最大上样体积为2.5 BV(BV为树脂体积),以70%乙醇3倍树脂体积洗脱。结论优选的提取、纯化工艺条件提取甘草有效成分,提取率高,工艺合理可行。     

An improvised process of isolation,purification of steviosides from Stevia rebaudiana Bertoni leaves and its biological activity

The food industry has traditionally used sugar (sucrose) as a sweetening agent; however the dietary and health demands are continuing to expand the market for sweeteners as an alternative to sucrose. The leaves of Stevia rebaudiana are rich source of glycosides that have sweet taste with low calorific value. The study highlights extraction of steviosides from leaves using pressurised hot water extractor, followed by purification and concentration of the sweet glycosides through ultra (UF) and nano (NF) filtration membrane in obtaining high purity steviosides. After the final purification process the stevioside content was 9.05 g per 100 g and rebaudioside A 0.2 g per 100 g stevia leaf, with total purity of stevioside 97.66% by HPLC at total operation time of 7 h. This process also improved the potency of sweetness and palatability profile when compare with other commercially available steviosides. Thus, the methodology developed establishes simple, in‐expensive and eco‐friendly process in obtaining pure steviosides.     

甜菊糖苷研究进展

甜菊糖苷是一种低热能的高倍甜味剂。本文综述了甜菊糖苷的来源、提取分离、结构、安全性及其检测方法等方面的国内外研究进展,在此基础上,提出了今后甜菊糖苷研究发展方向。     

蔗糖对酶法改性甜菊糖的影响研究

用节杆菌产β-呋喃果糖苷酶催化转果糖基作用,对甜菊糖进行分子改性。采用蔗糖和甜菊糖的混合反应体系,考察了不同浓度蔗糖对甜菊糖转化率的影响,并比较了间歇式补加固体蔗糖和连续流加蔗糖溶液对甜菊糖转化率的影响,对反应条件进行了优化。优化条件下,采用初始浓度为20%(W/V)的蔗糖反应,反应过程流加30%(W/V)蔗糖溶液,反应5h后,甜菊双糖A苷和甜菊苷的转化率均超过90%,反应过程中二者的最高转化率均可达98.6%。     

环糊精葡糖基转移酶法改性甜菊糖的研究

目的:优选环糊精葡糖基转移酶法对甜菊糖进行结构改变的工艺。方法:以甜菊苷酶改转移率为指标,通过对影响酶改性反应的pH、甜菊苷与淀粉的比例、反应温度、反应时间、酶的用量五个因素进行考察,首先确定pH以及甜菊苷与淀粉的比例对转化率的影响,对剩余三个因素采用正交设计考察,筛选了酶改性甜菊苷的最佳工艺。结果:最佳酶改工艺组合为:pH=6,淀粉与甜菊苷的比例为2∶1,反应温度40℃,反应时间24h,酶的用量为60u/g淀粉。结论:该方法能有效对甜菊苷进行酶改,工艺合理且操作简单。     

Production of steviosides in ex vitro and in vitro grown Stevia rebaudiana Bertoni

Stevia rebaudiana Bertoni plants grown in vitro and ex vitro were investigated for variations in the profile of steviosides in their leaves, shoots, roots and flowers. Steviosides were extracted by hydrolysis and esterification, evaporated to dryness and dissolved in methanol for quantitative analysis by high‐performance liquid chromatography (HPLC). The HPLC analysis and separation profiles indicated the presence of several different steviosides, predominantly eight known sweet diterpene glycosides. The most abundant compounds identified were steviolbioside, stevioside, rebaudiosides C and A and dulcoside A. The highest stevioside contents were recorded in 1‐month‐old greenhouse leaves (64.80 g steviolbioside kg^?1 dried plant material) and in vitro leaves (0.99 g rebaudioside A kg^?1 dried plant material). The recovery of steviosides from the leaves by methanol extraction was 90%. This is the first time that the eight predominant sweet diterpene glycosides in the various plant parts of S. rebaudiana have been investigated. Copyright © 2006 Society of Chemical Industry     

Analysis of Predominant Steviosides in Stevia rebaudiana Bertoni by Liquid Chromatography/ Electrospray Ionization-Mass Spectrometry

Stevia reabudiana is gaining popularity especially in making diabetic food supplements in view of its non-nutritive glycosides. Steviosides profile in ex vitro and in vitro leaves and callus cultures of S. rebaudiana were investigated by HPLC analysis and further confirmed by MS using mass spectral fragmentation data obtained from LC-MS-ESI studies. The leaf samples (4 weeks old) and callus cultures (2 weeks old) were used for extraction and extracts were used for HPLC analysis. Predominantly, eight sweet diterpene glycosides were detected. The highest stevioside content of 6.48% Steviolbioside and 0.099% Rebaudioside-A on a dry weight basis were found in ex vitro and in vitro leaves, respectively. In callus and suspension cultures, the biosynthesis of steviosides was observed except for steviolbioside. The LC-MS-ESI based detection of different steviosides in Stevia cultures could be used for comprehensive qualitative evaluation of the samples.     

甜菊糖代替高热量蔗糖的甜味功能研究

通过感官评定的方法研究甜菊糖的甜味特性及其在冰红茶饮料中取代蔗糖的应用效果。采用量值估计法对甜菊糖的相对甜度进行测定,得到不同等甜蔗糖浓度下甜菊糖的甜度倍数;采用喜好排序法对用甜菊糖替代蔗糖的冰红茶进行感官评定,结果显示,在不影响感官品质的情况下,0.462g/L的甜菊糖可以取代冰红茶饮料中60g/L的蔗糖,热量降低了67%,且与市售冰红茶饮料在感官喜好性方面并无显著性差别。     

Purification of Steviosides by Membrane and Ion Exchange Processes

An ultrafiltration (UF) process removed more than 96% of the pigments and recovered 45% of steviosides non-nutritive sweetener from an extract of leaves. UF retentate was further processed by diafiltration (DF), and the permeate was concentrated by reverse osmosis (RO). The membrane processes (UF, DF, RO) achieved an overall steviosides recovery of more than 90% with product purity 46%. Final purification was conducted by two consecutive mixed bed ion exchange processes. The ion exchangers improved purity of the final product to 90%.     

Stevioside and Stevia-sweetener in food: application, stability and interaction with food ingredients

The stability of the natural sweetener stevioside during different processing and storage conditions as well as the effects of its interaction with water-soluble vitamins, food relevant organic acids and other common low calorie sweeteners and its application in coffee and tea beverages were evaluated. Incubation of the solid sweetener stevioside at elevated temperatures for 1 h showed good stability up to 120°C, whilst at temperatures exceeding 140°C forced decomposition was noticed. In aqueous solutions stevioside is remarkable stable in a pH range 2–10 under thermal treatment up to 80°C, however, under strong acidic conditions (pH 1) a significant decrease in the stevioside concentration was detected. Up to 4 h incubation of stevioside with individual water-soluble vitamins in aqueous solution at 80°C showed no significant changes in regard to stevioside and the B-vitamins, whereas a protective effect of stevioside on the degradation of ascorbic acid was observed resulting in a significant delayed degradation rate. In the presence of other individual low calorie sweeteners practically no interaction was found at room temperature after 4 months incubation in aqueous media. Stability studies of stevioside in solutions of organic acids showed a tendency towards enhanced decomposition of the sweetener at lower pH values depending on the acidic medium. In a stevioside-sweetened coffee and tea beverage, practically, no significant chances neither in caffeine content nor in stevioside content could be noticed. Furthermore an overview of already performed studies in literature about the Stevia-sweetener stevioside and rebaudioside A is given.     

Modification of steviol glycosides using α-amylase

Stevia extract usually contains a high content of stevioside which produces a significant bitter aftertaste, thus limiting its commercial application as a high-potency sweetener in foods. In order to improve its organoleptic properties, the stevia extract (containing 90 g/100 g stevioside) was modified by α-amylase from Aspergillus oryzae (TAKA), with soluble starch as substrate. Stevioside was found to be an efficient acceptor substrate and has been transglycosylated during the reaction. The mono-glycosylated stevioside was the major product. The influences of reaction conditions on the conversion yield of stevioside, including pH, reaction temperature, weight ratio of stevioside to starch, substrate and enzyme concentrations, were investigated. With 2 g/100 mL stevioside and 20 g/100 mL soluble starch in 0.05 mol/L potassium phosphate buffer, pH 6.4 and 50 U/mL TAKA, 48.2% conversion yield of stevioside was obtained in 0.5 h at 70 °C. For the enzymatically modified steviol glycosides, the bitter aftertaste was significantly decreased and the sweetness potency was significantly improved.