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%。     

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.     

不同干燥工艺对酒糟干燥过程热效率的影响

通过对酒糟直接干燥和压榨干燥进行对比试验，采用热平衡理论分析计算不同干燥工艺对干燥过程热效率的影响。结果表明：压榨干燥比直接干燥时间平均缩短45％／1％水，能耗平均降低7．8％／1％水。说明合理选择操作条件对提高干燥器热效率、降低能耗是非常重要的。     

不同干燥工艺对生姜中5种姜辣素含量的影响

采用高效液相色谱法比较不同干燥工艺对生姜中姜酮、6-姜酚、8-姜酚、6-姜烯酚和10-姜酚5种姜辣素含量的影响。选用Grace smart RP C18(4.6 mm×250 mm×5μm)色谱柱,流动相为乙腈(B)-0.1%醋酸水溶液(A),梯度洗脱,流速为1.0 m L/min,检测波长280 nm,柱温30℃。结果显示:不同干燥工艺得到的生姜粉中姜酮、6-姜酚、8-姜酚、6-姜烯酚和10-姜酚5种姜辣素的总含量以冷冻干燥最高,干燥需要48 h,能耗大;60℃红外干燥次之,干燥只需1.5 h,效率高。不同的干燥工艺对生姜中5种姜辣素的总含量有明显影响;生姜的干燥以60℃红外干燥为宜。     

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。     

甜味剂莱鲍迪苷D的高效生物催化合成

采用来自水稻的UDP-糖基转移酶EUGT11并结合染色体改造构建了大肠杆菌工程菌,用于全细胞催化莱鲍迪苷A(Rebaudioside A,RA)生产莱鲍迪苷D(Rebaudioside D,RD)。为了增加宿主细胞内源性糖配体葡萄糖尿苷二磷酸(uridine diphosphate glucose,UDPG)的供给以满足糖基化反应需要,以大肠杆菌BL21(DE3)为出发菌对UDPG代谢通径进行改造,获得了一系列改造菌株SG1、SG2、SG3和SG4。其中以SG4为宿主过表达可高效催化RA合成RD的糖基转移酶EUGT11进行全细胞催化,RD产量高。随后以此工程菌为对象,对可能影响RD催化合成的条件进行了研究,结果表明50 m L培养菌液离心所收集新鲜菌体可在100 mmol/L pH 8.0磷酸钠缓冲液、80 mmol/L柠檬酸钠、体积分数0.1%Triton X100、500 g/L蔗糖、5 mmol/L Zn Cl2、42℃转化1 d的条件下催化1 mmol/L RA底物生成1112.21 mg/L RD,转化率可达98.5%。     

干燥工艺对酒糟热效率的影响

通过对酒糟直接干燥和压榨干燥进行对比试验,并采用热平衡理论分析计算不同干燥工艺对干燥过程热效率的影响,结果表明:压榨干燥比直接干燥时间平均缩短45%/1%水,能耗平均降低7.8%/1%水。因此,合理选择操作条件,对提高干燥器热效率,降低能耗是非常重要的。     

在服装网络定制中RA对客户满意度的影响

产品推荐代理(RA)是商家为了加快消费者决策而提供的隐形推荐系统。在服装网络定制系统中,RA给客户提供具有针对性的服装信息,减少因网站信息过载而给客户造成的压力。针对国内网络定制客户,构建了RA推荐系统、客户满意度及客户忠诚度三者之间的关系概念模型。研究结果表明:推荐系统质量好坏与客户满意度之间呈现正相关关系,且定制网站形象、推荐系统信息编排合理性削弱消费者对过量信息的敏感度,以及定制服装本身质量好坏直接影响消费者对定制行为的态度。另外,消费者自身对信息判定能力较强,会在一定程度上降低对RA推荐系统的依赖性。     

不同干燥工艺对鲜玉米粉品质及风味的影响

本文研究了煮后烘干、炒制和冻干加工对鲜玉米粉的基本成分、抗氧化性能和香气成分影响。结果表明:不同干燥工艺鲜玉米粉的淀粉、总糖、总黄酮和总酚含量差异显著(P<0.05),冷冻干燥鲜玉米粉总黄酮和总酚含量最高,分别为3.45和3.96 mg/g。冷冻干燥、煮后烘干的鲜玉米粉对DPPH自由基的清除率分别为60.5%、50.8%,对·OH的清除率分别为46.8%和39.6%。运用固相微萃取-气相色谱-质谱联用对鲜玉米粒和3种干燥工艺的鲜玉米粒的香气物质进行分析,共鉴定出79种挥发性物质,分别为醇类3种、醛类11种、酮类8种、烃类24种、酯类8种、杂环类25种。含苯环类芳香族化合物是鲜玉米的主体风味化合物。综合分析,冷冻干燥和煮后烘干的鲜玉米粒抗氧化能力较高,对于鲜玉米芳香族化合物也有较好保留。     

脱蜡工艺对枸杞热风干燥时间的影响

脱蜡处理为枸杞干燥前处理工艺中重要环节之一,影响枸杞干燥速率和干燥品质。为获得更短的干燥周期和更好的干燥品质,以温度、时间、溶液比为实验因素,进行枸杞脱蜡单因素实验和Box-Behnken Design响应面优化法研究。结果表明,枸杞最优脱蜡参数组合为脱蜡时间12 min,脱蜡温度38℃,脱蜡溶液比1∶2,在此条件下干燥时间为21.5 h。验证实验和品质鉴定结果显示,最优脱蜡工艺缩短了枸杞的干制时间,保留了枸杞营养成分。      

甜叶菊水提取液的絮凝研究

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:温度为65~70℃,pH值为9~10,添加絮凝剂用量为4.5g/L,作用时间为40min左右。     

Biological activity of Stevia rebaudiana Bertoni and their relationship to health

The leaves of Stevia rebaudiana Bertoni has nutrients and phytochemicals, which make it an adequate source for the extraction and production of functional food ingredients. Preclinical and clinical studies suggest therapeutic and pharmacological applications for stevia and their extracts because they are not toxic and exhibit several biological activities. This review presents the biological activity of Stevia rebaudiana Bertoni and their relationship to antidiabetic, anticariogenic, antioxidant, hypotensive, antihypertensive, antimicrobial, anti-inflammatory and antitumor activities. Consumption and adverse effects were also reviewed.     

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.     

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     

甜叶菊毛状根培养系统的建立及绿原酸类成分的诱导

本文利用发根农杆菌A4诱导甜叶菊毛状根再生,建立毛状根生产绿原酸类物质的培养体系,并研究茉莉酸甲酯和水杨酸对毛状根中绿原酸类物质积累的影响。结果表明,经发根农杆菌A4侵染的甜叶菊叶片外植体在共培养14 d后诱导出了毛状根;PCR检测结果表明,发根农杆菌Ri质粒中rolB和rolC基因均已整合到毛状根中;毛状根在MS液体培养基中,培养到第14 d时分别加入不同浓度（50、100、200 μmol/L）的水杨酸和茉莉酸甲酯进行诱导,处理第1、3、6 d后均抑制了毛状根的生长,但茉莉酸甲酯促进了毛状根中绿原酸类物质的积累,而水杨酸却抑制了毛状根中绿原酸类物质的积累。由此说明,发根农杆菌A4侵染甜叶菊可诱导出毛状根,该毛状根可用于绿原酸类物质的生产,茉莉酸甲酯可提高绿原酸类物质的含量。     

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...     

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。     

The influence of natural sweetener (Stevia rebaudiana Bertoni) on bioactive compounds content in chokeberry juice

The aim was to determine the differences in nutritional quality between chokeberry juices sweetened with sucrose and green stevia powder. The quality of chokeberry juices during refrigerated storage was studied. Chokeberry juices with added green stevia powder had the higher content of analyzed bioactive compounds in comparison with juice samples sweetened with sucrose; vitamin C content increased up to two times, total phenol content up to 6% and antioxidant capacity for 3%. The content of studied bioactive compounds and antioxidant capacity during storage in period of 30 and 60 days was significantly reduced with the exception of steviol glycosides which content was not significantly reduced during the storage period.

Practical applications

Chokeberry juice is a popular, widespread product of chokeberry fruit characteristic for the dark intense red color, slightly unpleasant, bitter taste and extremely rich bioactive compounds content. Because of high nutritional quality, chokeberry juice is often consumed but with the biggest barrier of characteristic astringent taste which can be diminished by addition of sweetener. Producers often combine a low‐cost sweeteners like sucrose which shows numerous negative effects on human health. A good alternative to the sucrose and artificial sweeteners are natural sweeteners extracted from the plant material like steviol glycosides. Except sweetness, stevia products like green powder shows beneficial effect on the bioactive compounds content in the juices sweetened with it. Juices sweetened with stevia shows increased content of bioactive compounds, so such product may represent quality product from category of functional food.     

甜叶菊随机扩增多态性DNA技术优化及亲缘关系研究

以甜叶菊为试材,对影响其随机扩增多态性DNA标记反应体系的7个因子进行优化,同时对来自国内外的12个品种进行亲缘关系分析。结果表明,20μL的优化体系包括:双蒸水13.6μL,10×Buffer(含15mmol/LMgCl2)溶液3μL,2.5mmol/L的dNTPS1.2μL,10μmol/L的引物1μL,20ng的模板DNA1μL,1UTaq聚合酶;热循环程序为:94℃预变性4min,94℃变性30s,35℃退火30s,72℃延伸1min,40个循环,最后72℃延伸7min。聚类图结果表明,品种间的遗传距离变异范围为0.12～0.88,在遗传距离为0.37时,8个引物可将12个品种分为四大类,来自日本的2个品种与国内品种关系较远。