微波提取茶叶中咖啡因工艺的研究

采用微波提取方法，微波功率为500W，以茶叶中提取咖啡因的含量为考察指标，研究提取溶剂浓度、料液比、提取时间等因素对咖啡因提取率的影响。通过正交试验，确定微波提取茶叶中咖啡因的最佳工艺条件为：提取溶剂50％乙醇，料液比1：8，提取温度180℃，提取时间14min。     

茶叶废料中提取天然咖啡因的研究

采用新工艺，从茶叶废料中提取天然咖啡因，考察了浸取时间、碱用量、萃取剂对产品收率的影响。     

高效液相色谱法测定与比较5种不同提取方法提取的茶叶咖啡因

建立高效液相色谱（high performance liquid chromatography，HPLC）法测定5种不同提取方法提取的茶叶咖啡因，比较分析不同提取方法对咖啡因提取物纯度和含量的影响。测定咖啡因的含量在浓度范围10 μg/mL～120 μg/mL呈现良好的线性关系，相关系数为0.999 9，5种咖啡因样品在3个浓度添加水平下的加标回收率为92.47%～109.07%，相对标准偏差（relative standard deviation，RSD）为0.11%～2.77%。该方法准确度和精密度较高，能准确分析不同咖啡因提取物之间的差异，适用于咖啡因提取物的分析与比较。5种提取方法提取的咖啡因含量和纯度有一定差异，丙酮水溶液提取-氯仿萃取法的提取效果最佳。     

茶叶多糖的微波辅助提取技术研究

以微波辅助提取技术,分别考查了提取溶剂、微波功率、提取时间、固液相比等因素对提取茶叶多糖效果的影响,并与热水浸提法进行比较。结果表明在微波辅助下,水和20%乙醇提取多糖的效果好,微波功率越高越有利于多糖提取,总提取时间以60 min以上为宜,液固相比达到15∶1即可。该技术与传统热水浸提法相比较,提取率高,节省时间,明显提高了提取效率。     

茶叶多糖的微波辅助提取技术及降血糖功能研究

以微波辅助提取技术,分别考查了提取溶剂、微波功率、提取时间、固液相比等因素对提取茶叶多糖效果的影响,并与热水浸提法进行比较.结果表明在微波辅助下,水和20%乙醇提取多糖的效果好,微波功率越高越有利于多糖提取,总提取时间以60min以上为宜,液固相比达到151即可.该技术与传统热水浸提法相比较,提取率高,节省溶剂,明显提高了提取效率.茶叶粗多糖对正常小鼠空腹血糖水平有一定的降低作用,但作用强度较弱,且维持时间较短;对小鼠淀粉和葡萄糖负荷糖耐量均有明显的改善作用.     

液相色谱法分析茶叶中咖啡因的含量

文章采用高效液相色谱法分别测定云雾绿茶、碧螺春、黄山毛峰、六安瓜片、信阳毛尖、铁观音茶叶中咖啡因含量的方法,根据咖啡因易溶于二氯甲烷的性质,用二氯甲烷作为提取剂,方法采用ZORBAXEclipsepiusC18柱,以CH3OH-H2O(50:50)溶液做流动相,紫外检测波长为230nm该条件下咖啡因保留时间为1.252min,经过实验得出线性回归方程为:y=5335.57746x+9.7548534,相关系数r=0.99955。方法线性良好。结果表明,不同茶叶中咖啡因的含量也不同,本方法简便、准确,适合茶叶提取物中咖啡因含量的分析。     

微波法从茶叶中提取茶多酚

介绍了以绿茶茶末为原料，以乙醇为介质，用微波加热法提取茶多酚，并通过改变溶剂浓度、微波功率、提取时间等条件对产品提取率的影响进行了探讨，获得最佳的提取条件。结果表明，料料比(w／v)1：9，时间18s，微波浸提2次，茶多酚浸提率达92．7％，该方法与传统提取方法相比，提取率高，省溶剂，大大提高了提取效率。     

离心萃取法测定茶叶中的咖啡因

建立一种茶叶咖啡因含量的测定方法.采用正交设计确定茶叶咖啡因测定的最佳条件为:每毫升样液加入15.0 mL 三氯甲烷,在5 000.0 r/min条件下离心5.0 min、萃取2次.方法的加标回收率为99.30%～101.54%.该法和国家标准方法测定同一茶叶样品咖啡因含量,结果差异不显著.     

茶叶香气提取方法

目前已鉴定的茶叶挥发性成分有700种左右,茶叶香气是由挥发性成分以一定的比例和含量组成的混合物,进而呈现出不同的茶叶风味。香气是茶叶的灵魂,关乎茶叶品质的优劣,影响消费者喜好度和选择性。茶叶挥发性成分的有效提取是研究茶叶风味及香气性能的关键,采用合适的茶叶香气提取方法,完整地萃取、富集真实茶香,有助于茶叶香气成分鉴定和分析。本研究综述了主要的茶叶香气提取方法,对其特点、应用性能进行了概述和总结,并提出了真实茶叶香气萃取的基本策略。     

高效液相色谱法测定茶叶及其提取物中咖啡因含量

茶叶中含咖啡因，用超临界CO2提取茶叶中咖啡因的研究中，需要对茶叶原料和茶叶提取物中的咖啡因进行分析和测定，为配合科研工作，进行了分析方法的实验和研究，建立了专门用于分析咖啡因的高效液相色谱方法，该分析方法具有高效快速，价廉，重现性好，准确试高的特点。     

普洱茶发酵过程中微生物总DNA提取方法的比较

为了快速提取普洱茶发酵过程中微生物总DNA,便于分析微生物群落的多样性及演替情况,对比研究了总DNA提取的四种方法-酶法、试剂盒法、超声波法和变性剂法,以16S rRNA区域通用引物(27F和1492R)和18S rRNA区域通用引物(NS1和NS8)对四种方法提取的总DNA分别进行扩增,根据总DNA提取的大小、产量、纯度和PCR扩增产物进行评估。综合各项指标来看,总DNA提取方法以变性剂法为优,其次是试剂盒法、超声波法和酶法。     

龙井绿茶咖啡碱的提取工艺研究

通过研究龙井绿茶中咖啡碱的几种提取方法,选择和优化工艺条件,为从绿茶中提取咖啡碱的工业化提供一定的参考,首先验证了索氏抽提法提取龙井绿茶中咖啡碱的有效性,其次分别研究了微波辅助和超声波辅助提取茶叶中咖啡碱的优化工艺。结果表明：微波浸提咖啡碱的最佳浸提条件为：液固比20∶1,微波解冻档辐照3min,浸提3次,最高浸提率为3.69%;超声波最佳浸提条件为：超声功率100%,超声波处理时间为25min,浸提2次,液固比为25∶1,超声温度为80℃,最高浸提率为3.77%。微波和超声波浸提效果明显高于索氏浸提,但微波浸提与超声波浸提的提取率相差不大。     

微波辅助循环萃取法脱除茶叶咖啡因研究

探讨了利用微波辅助萃取技术高选择性脱除茶叶中咖啡因的新方法,在料液比1∶50,微波功率160W,微波时间6min的条件下,以沸水为溶剂,咖啡因脱除率高达80.56%,茶多酚损失率为40.16%。优化工艺以茶叶萃取液为溶剂,采用循环萃取的方式,则可以控制茶多酚损失率降至12%。进一步探索性尝试4℃冷藏静置12h的方法进行萃取液循环利用,促使咖啡因以络合物的形式沉淀、脱除。在最优条件下,连续生产茶叶9批次后仍可保持47.02%的脱除率,并且茶多酚的损失率小于11.74%。     

Comparison of extraction and isolation efficiency of catechins and caffeine from green tea leaves using different solvent systems

Catechins from green tea (Camellia sinensis L.) have received considerable attention due to their beneficial effects on human health, such as antioxidant and anticancer activities. Optimisation of extraction conditions of the catechins from green tea leaves was performed using different solvents (ethanol or distilled water), different extraction methods (ultrasound‐assisted, room temperature or reflux extractions) and various extraction times (0.5–24 h). The optimal extraction conditions were determined using 40% ethanol with ultrasound‐assisted extraction method for 2 h at 40 °C. In addition, two isolation methods for the recovery of catechins from green tea extracts were compared using different solvent combinations (chloroform/ethyl acetate versus ethyl acetate/dichloromethane). The results showed that the ethyl acetate/dichloromethane system could achieve much higher content of catechins than the other isolation approaches, indicating the method that extract catechins first with organic solvent such as ethyl acetate before removing caffeine is much effective than removing caffeine first when organic solvents are used for the recovery of catechins without caffeine from green tea extracts.     

Column-chromatographic extraction and separation of polyphenols, caffeine and theanine from green tea

A highly efficient column-chromatographic extraction (CCE) followed by sequential adsorption to extract and separate bioactive compounds from green tea was developed. Tea powder was loaded into columns with 4-fold solvents and eluted through a cyclic CCE. High-quality tea extracts with greater than 90% extraction efficiencies of polyphenols, epigallocatechin-3-gallate, caffeine, theanine and polysaccharides were obtained with 4-fold water circulated five times among different columns at 70 °C. Similar results, except for low polysaccharide extraction (35.5%), were obtained with 4-fold 30% ethanol circulated three times at room temperature. The highly concentrated water extraction was directly passed through columns of polyamide, DM130 macroporous and 732 ion exchange resins, resulting in high-purity polyphenols (99%), caffeine (98%) and theanine (98%) after simple purification of the eluates from each column. This method uses simple equipment, minimum solvents and can be used for both quantitative analysis and continuous preparation of high-quality tea extracts and bioactive compounds.     

茶叶中茶多糖茶多酚茶咖啡碱的高压脉冲电场快速提取

以10倍质量的0．001MEDTA缓冲液为提取液，应用高压脉冲电场（PEF）技术成功从等外绿茶中提取功能成分茶多糖、茶多酚和咖啡碱，并与水提法的提取率进行了比较。结果表明：在缓冲液pH9．5，场强度为25kV／cm，脉冲数为10的条件下，茶多糖有最大提取率，PEF法提取率是水提法的1．91倍；在缓冲液pH9．5，脉冲电场强度为25kV／cm，脉冲数为12时，茶多酚有最大提取率，提取率是水提法的1．11倍；在缓冲液pH4．0，脉冲电场强度为25kV／cm，脉冲数为10时，咖啡碱有最大提取率，是水提法的1．05倍。     

姜辣素不同提取方法的比较研究

对姜粉中姜辣素提取的不同方法进行了比较研究。分别采用了回流法、微波辅助法和超声波辅助法3种不同方法进行了提取。其中超声波辅助法的提取率最高,达到7.28mg/g。     

辣椒碱不同提取方法的比较研究

文章对辣椒碱提取的不同方法进行了比较研究.采用了有机溶剂法、碱性乙醇法、超声波法、酶法及超临界流体法5种不同方法进行了提取.与其它方法相比,碱性乙醇法不仅提取时间短,提取率高,而且操作方便,适合大规模生产应用.     

Solid–liquid extraction of caffeine from tea waste using battery type extractor: Process optimization

This article deals with solid–liquid extraction of caffeine from tea waste containing 2% (w/w) caffeine using water and chloroform as effective solvents. The extraction has been performed at isothermal conditions of 370 K for water and 293 K for chloroform in the battery type extraction plant including both three and five extractors connected in series. An obvious difference in extraction behavior has been observed for two solvents, distinguishing the divergent interactions attributed to the different mechanism of solvent–caffeine aggregation. The high degree of separation of caffeine by chloroform is feasible with the efficiency ranging about two times larger than water in terms of the solvent flow rates tested. The optimum process parameters were estimated through the graphical interpretation of dependently changing variables, composition, flow rate and extraction degree. Details underlying some aspect of selection of an appropriate differential equation for fitting the data are discussed.     

从微藻中提取粗脂的方法比较

采用改良的酸水解法、异丙醇法、乙醇法、乙醚-石油醚法、索氏抽提法5种方法对3株微藻的粗脂含量进行测定。结果表明,改良的酸水解法与索氏抽提法提取效果稳定、粗脂提取程度高。与索氏抽提法相比,改良的酸水解法大大节省了测定时间,且可以同时对多个样品进行测定,是实验室中对多个微藻样品粗脂含量快速测定的首选方法。