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。     

两步树脂法从甜叶菊水提液中纯化甜菊糖苷

采用两步树脂法从甜叶菊水提液中提取纯化甜菊糖苷。第一步主要是脱色,通过比较大孔树脂D293、D296、JN-1、JN-2、D890和D201处理甜叶菊水提液的脱色率、甜菊糖苷保留率和解吸性能,发现JN-1的效果最好。在优化条件下,甜叶菊水提液经JN-1处理,甜菊糖苷纯度由原来的42.65%提高到67.33%,收率达到84.87%;第二步的主要目的是提高产品纯度,通过比较大孔树脂AB-8、JNF-1、X-5、NKA-II和D101对甜菊糖苷的吸附-解吸性能和得到的纯化液的甜菊糖苷纯度,发现JNF-1的效果最好。在优化的条件下,JN-1处理后的甜菊糖苷溶液进一步采用JNF-1吸附,溶液的甜菊糖苷纯度提高至92.92%,收率91.08%。     

壳聚糖对金银花水提液中绿原酸和微量元素含量的影响

采用IRIS/AP全元素扫描法测定金银花水提液中微量金属元素的含量.金银花水提液含有丰富的Ca2 、Mg2 和Zn2 离子.为研究金银花水提液的澄清工艺,研究壳聚糖处理中Ca2 、Mg2 和Zn2 离子和绿原酸含量的变化规律,讨论壳聚糖作用时间、用量和pH的影响.结果发现,在实验条件下,水提液中的Ca2 、Mg2 和Zn2 的吸附损失很大,其中Zn2 的吸附损失最高.壳聚糖用量、作用时间和pH对3种离子吸附损失有影响.延长处理时间和提高pH可以降低损失.此外,壳聚糖处理过程中,提取液的绿原酸含量也有一定的损失.     

甜叶菊功能性成分研究进展

甜叶菊含有多种功能性成分,包括糖苷类化合物、黄酮类化合物、绿原酸类等。甜菊糖苷作为甜味剂在食品、医药行业有重要的应用价值,黄酮类和绿原酸类物质也具有抗氧化、抗炎、抗癌等活性,具有开发潜力。本文对这三种物质在甜叶菊中的提取分离应用进行了综述。     

甜叶菊糖苷水提工艺的优化

以甜叶菊糖苷的水提浸出率为参考指标,通过单因素和正交设计优化甜叶菊糖苷的水提工艺,得到最优的水提条件为:提取温度70℃、提取时间3h、料液比1:15,在此条件下甜叶菊糖苷的水提浸出率可达到97%。     

甜叶菊花和叶中酚类成分分析及含量测定

以高效液相色谱-串联四极杆质谱分析仪,结合质谱分析及比对对照品或文献报道化合物的保留时间和质谱参数,在甜叶菊花和叶中鉴定了16种酚类化合物。建立一种利用高效液相色谱法测定甜叶菊中16种酚类化合物含量的方法,并对甜叶菊一新品种盛花期花和叶中酚类的含量进行测定。结果表明,甜叶菊花和叶中酚酸化合物以新绿原酸、绿原酸、隐绿原酸、异绿原酸B、异绿原酸A、异绿原酸C为主,异绿原酸A含量最高,绿原酸含量次之;花和叶中类黄酮化合物主要为芦丁、槲皮素-7-O-葡萄糖苷、木犀草素-7-O-葡萄糖苷、木犀草素-7-O-芸香糖苷、槲皮素-3-O-木糖苷、槲皮素-3-O-鼠李糖苷、芹菜素-7-O-葡萄糖苷、山奈酚-3-O-阿拉伯糖苷、山奈酚-3-O-鼠李糖苷,槲皮素-3-O-鼠李糖苷含量最高;盛花期甜叶菊花和叶中酚类总量达（22.31±0.51）mg/g和（91.11±2.32）mg/g。     

高效液相色谱法测定甜叶菊叶片中甜菊糖苷含量

为检测化学调控下甜叶菊叶片中不同甜菊糖苷的含量,建立了快速分析甜叶菊叶片中3种甜菊糖苷含量的高效液相色谱测定方法。液相色谱分析采用Sepax HP-Amino(4.6×250 mm,5μm)色谱柱,柱温40℃,流速1.00 mL/min,流动相采用等度洗脱模式,流动相乙腈/水组成比为80∶20(v/v),检测器为紫外-可见检测器,检测波长210 nm,谱带宽度20 nm,狭缝宽度16 nm,进样体积4μL;样品采用超声波辅助热水提取,澄清石灰水去除杂质。结果表明液相色谱分析得出3种甜菊糖苷(甜菊糖苷、莱鲍迪苷C、莱鲍迪苷A)线性方程分别为Y=1.075X-1.853(r=0.999 9)、Y=1.302 X+1.136(r=0.999 5)和Y=1.117X+1.089(r=0.999 8),在0.05～5.00 mg/mL之间线性关系均表现良好,方法检测限分别为1.091μg/mL,3.062μg/mL和1.078μg/mL。所建方法简单灵敏,适合叶片样品快速检测。     

壳聚糖对川芎提取液澄清效果的影响

采用壳聚糖对川芎提取液进行澄清,通过单因素实验和正交实验对其工艺进行了优化,探讨了壳聚糖用量、p H和温度对提取液透光率和川芎嗪保留率的影响。结果表明:川芎提取液澄清的最佳条件是壳聚糖用量1.33g/L,p H4.0,温度50℃,在此条件下,川芎澄清液透光率高达62.7%,川芎嗪保留率为72.3%,壳聚糖澄清川芎提取液的效果较好,川芎的有效成分也得到了较好的保留。     

水提醇沉法从甜叶菊中提取甜叶菊甙的改进法

一、前言水提醇沉法从甜叶菊提取甜叶菊甙的工艺是热水浸提,沉淀剂去杂脱色,减压浓缩至约45～50%的溶液,加入95%的酒精使液中的乙醇含量达70%以上,进一步沉淀去杂脱色,所得酒精溶液经活性炭脱色后,减压蒸馏至干得淡黄色的粉状粗甜叶菊甙。改进方法是热水浸提,选用无毒害,去杂脱色能力强,且对甜叶菊甙吸附极小的沉淀剂反复进行去杂脱色,可得淡黄色的甜味水溶液,经减压蒸馏至干得淡黄色粉状粗甜叶菊甙。改进方法不使用乙醇和活性炭,可概括为水提沉淀剂去杂脱色法。此法所得淡黄色粉状粗甜叶菊甙,苦涩味、吸湿味、吸湿性有了明显地降低,且具有一定的咖啡香味,质量基本接近水提醇沉法所得成品。     

壳聚糖对竹荪水提液中镉的去除及其机理研究

为探讨壳聚糖对竹荪水提液中镉的去除及其去除机理。以竹荪水提液为研究对象,利用壳聚糖吸附其中的镉,以镉吸附率和粗多糖保留率作为指标,在单因素的基础上,进行p H、壳聚糖添加量、吸附温度和吸附时间的四因素三水平正交实验,并探究了壳聚糖吸附前后的竹荪水提液中镉形态的变化。结果表明:最佳吸附条件为:p H7.0、壳聚糖添加量0.35 g/100 m L、吸附温度70℃、吸附时间2.5 h,在此条件下,镉吸附率为63.8%,粗多糖保留率为85.6%,镉含量达到食品安全标准限量的要求;形态分析结果显示壳聚糖主要吸附竹荪水提液中游离态、无机态和稳定态的镉。表明壳聚糖对竹荪水提液中镉具有较好的吸附效果,且对功效成分粗多糖的影响较小。     

Polyphenols from Stevia rebaudiana (Bertoni) leaves and their functional properties

The major polyphenol components from Stevia rebaudiana (Bertoni) leaves (PPS) are chlorogenic acids, a polyphenol family of esters, including hydroxycinnamic acids with quinic acid, which possesses excellent hydrophilic antioxidant activity and other therapeutic properties. As an abundant byproduct during production of steviol glycosides, the PPS would be a new antioxidantive food resource or additives applied in foods and drugs with antidiabetic function. Extracting PPS from S. rebaudiana (Bertoni) leaves together with steviol glycosides would be an economic process, which will change most operation process in current Stevia factories. The quantification of PPS needs to be unified for regulation. In view of the current regulation status of polyphenols and extracts from Stevia, the PPS would be ready to go to the market with few regulation barriers in the near future. This review will summarize the analysis, extraction, and some functional properties of PPS, such as antioxidant, antidiabetic, antimicrobial, anti-inflammatory, and anticancer.     

甜叶菊红外-热风联合干燥工艺优化

为探究甜叶菊红外-热风干燥特性,以江西甜叶菊守田3号为试验材料,在研制的红外-热风联合干燥样机基础上,通过开展热风温度(90、100、110、120℃)、排湿功率(0、140、240、340 W)和辐射距离(140、150、160、170 mm)条件下的单因素和正交试验,探究甜叶菊红外-热风干燥特性曲线及干燥速率曲线,优化甜叶菊干燥工艺参数。结果表明,甜叶菊红外-热风联合干燥过程包含预热加速干燥阶段和降速干燥阶段;影响甜叶菊红外-热风联合干燥生产效率的影响因素顺序为:热风温度 > 辐射距离 > 排湿速率;最佳干燥工艺参数:热风温度120℃,排湿功率240 W、辐射距离140 mm,此时甜叶菊干燥时长6.57 min,能耗1.25 kW·h。本研究可为研制甜叶菊干燥装置和研究甜叶菊干燥特性提供参考。     

Steviol glycosides are not altered during commercial extraction and purification processes

Steviol glycosides, sweet diterpenes extracted from the shrub Stevia rebaudiana Bertoni, are approved as sweeteners in many countries throughout the world. Former heat and pH‐investigations of these glycosides have established their stability. However, due to the complex purification process, the natural authenticity has still been discussed and challenged, recently. Thus, the objective of this work was to show that the steviol glycosides are not chemically modified during the commercial extraction and purification process. Therefore, samples of three independent commercial‐scale extraction and purification batches of steviol glycosides, each batch containing a sample of the untreated stevia leaves, the first water extract and the high‐purity end product, were analysed using HPLC‐UV and HPLC‐ESI‐MS/MS. The results show that the commercial powders of extracted steviol glycosides with an estimated purity of more than or equal to 95% contain the same steviol glycosides as the dried stevia leaves and their hot water infusions, demonstrating that steviol glycosides are not affected by the purification process.     

Separation of Steviol Glycosides by Hydrophilic Liquid Interaction Chromatography

Stevia rebaudiana Bertoni contains several steviol glycosides with sweet flavour. They all are sweeter than sucrose (up to factor 450). The various steviol glycosides are difficult to separate by reversed-phase chromatography. In this paper, five different hydrophilic liquid interaction chromatography columns are characterized using isocratic elution (5–20% water in acetonitrile with buffer or formic acid). Separation of the steviol glycosides is possible with all but one of the tested columns, but the robustness of the separation against changes of buffer concentration and percentage of water differ. Aqueous percentage and ion strength of the eluent are the main factors to be optimized in method development.     

甜叶菊毛状根的诱导培养及茉莉酸甲酯对其绿原酸类物质积累的影响

以发根农杆菌ACCC10060诱导甜叶菊毛状根,建立毛状根培养生产绿原酸类物质体系,研究茉莉酸甲酯对绿原酸类化合物积累的影响。经发根农杆菌ACCC10060侵染的甜叶菊叶片外植体,共培养14 d后产生毛状根。聚合酶链式反应检测结果表明,发根农杆菌Ri质粒的rol B和rol C基因已成功整合到甜叶菊毛状根基因组中。MS液体培养基较B5、WPM更利于甜叶菊毛状根生长及绿原酸类物质的积累,培养35 d后,干质量增加约30倍,绿原酸、3,5-二咖啡酰奎宁酸、4,5-二咖啡酰奎宁酸最高含量分别为3.47、11.47、3.04 mg/g。毛状根在MS液体培养基中培养至第3周时分别添加15、45、100μmol/L的茉莉酸甲酯进行诱导,处理后第1、2、4、8天收获,毛状根的生长量和绿原酸类物质含量均有提高,其中以45μmol/L茉莉酸甲酯的促进作用最为显著,3种绿原酸类物质的总产量是对照组的2.68倍(P0.01)。以上结果表明,甜叶菊毛状根培养可用于绿原酸类物质的生产,经茉莉酸甲酯处理可显著提高绿原酸类物质的产量。     

甜叶菊提取液的絮凝工艺研究

研究了絮凝剂在甜叶菊提取液的澄清过程中的作用，选出最适絮凝剂，并对其澄清效果进行实验，确定了最佳的絮凝条件。     

甜菊糖苷类物质的功能性研究进展

甜菊糖苷是一类从甜叶菊叶子中提取的高甜度、低热值的甜味剂,是一种非常理想的蔗糖替代品。毒理学实验表明,甜菊糖苷不具有致畸、致癌和致突变毒性。除了作为优良的甜味剂应用在食品、饮料中,甜菊糖苷还表现出许多功能活性,如降血压、降血糖、抗肿瘤、抑菌、抗腹泻、增溶等。由于甜菊糖苷的结构可调性,可以对其进行定向修饰,得到更多具有潜在应用价值的衍生物,这方面的研究对于甜菊糖苷的深入开发利用具有重要意义,本文将围绕近几年有关甜菊糖苷功能性的研究展开讨论。     

Stevia rebaudiana Bertoni, source of a high-potency natural sweetener: A comprehensive review on the biochemical, nutritional and functional aspects

Stevia rebaudiana Bertoni, an ancient perennial shrub of South America, produces diterpene glycosides that are low calorie sweeteners, about 300 times sweeter than saccharose. Stevia extracts, besides having therapeutic properties, contain a high level of sweetening compounds, known as steviol glycosides, which are thought to possess antioxidant, antimicrobial and antifungal activity. Stevioside and rebaudioside A are the main sweetening compounds of interest. They are thermostable even at temperatures of up to 200 °C, making them suitable for use in cooked foods. S. rebaudiana has a great potential as a new agricultural crop since consumer demand for herbal foods is increasing and proximate analysis has shown that Stevia also contains folic acid, vitamin C and all of the indispensable amino acids with the exception of tryptophan. Stevia cultivation and production would further help those who have to restrict carbohydrate intake in their diet; to enjoy the sweet taste with minimal calories.     

Improving drying efficiency and product quality of Stevia rebaudiana leaves using innovative medium-and short-wave infrared drying (MSWID)

The effects of hot air impingement drying (HAID), hot air drying with temperature and humidity process control (HADTHPC), medium-and short-wave infrared drying (MSWID), shade drying (HD) and sun drying (SD) on the drying characteristics and physicochemical quality of Stevia leaves were investigated, MSWID was screened out most suitable for Stevia leaves drying. The relationships among drying time, microstructure, color and nutrients retention were analyzed. Compared with other drying methods, MSWID significantly reduced drying time by 15.38% and better preserved the nutrients (steviol glycosides and chlorogenic acids) due to the formation of a distinct microporous structure. Moreover, medium wave infrared (MIR) drying was superior to short wave infrared (SIR) in retaining steviol glycosides and color and improving drying efficiency. Brightness and greenness of dried Stevia leaves were significantly correlated with glycosides and chlorogenic acids content, respectively. MIR at 60 °C is recommended as the most suitable drying conditions due to the highest comprehensive score (0.723) considering drying time, energy consumption and quality. Overall, MSWID is a promising drying technology for realizing high-quality and efficient industrial production of Stevia leaves.