Effects of High-intensity Pulsed Electric Field on Amino Acid Content in Large-leaf Pu'er Tea Variety

[Objective] This study aimed to test the effects of high-intensity pulsed electric field on the amino acid content in Pu’er tea leaves. [Method] The amino acid contents of fermented and unfermented the leaves of large-leaf Pu’er tea variety produced in Yunnan Mengku, were measured before and after the treatment with high-intensity pulsed electric field （HPEF）. [Result] The difference of amino acid contents was notable between fermented and unfermented tea leaves produced in the same year. The amino acid content of unfermented tea leaves was larger than that in fermented tea leaves. The amino acid content in tea leaves decreased over time during storage. HPEF treatment under al the conditions improved the amino acid content in tea leaves. [Conclusion] This experiment provides theoretical foundation for the application of HPEF in processing of Pu’er tea leaves.

Inhibitory Effects of Pu-erh Tea Leaves on Mouse Type IV Allergy

Pu-erh tea is one of post fermented tea manufactured through oxidative maturing by microorganisms. We investigated the preventive effects of pu-erh tea extract on oxazolone-induced type IV allergy in male (ICR) mice. Oral administration of 50 mg/kg water extract of pu-erh tea leaves resulted in significant preventive effects against mouse type IV allergy. The hydrophilic Theabrownin-like fraction (TBW-ND), with a high molecular weight of approximately 12,000 or higher, was prepared from pu-erh tea leaves by a solvent-extraction method, followed by Diaion HP-20 column chro-matography and dialysis. Oral and percutaneous administrations of TBW-ND at doses of 18.7 mg/kg and 0.037 mg/ear also resulted in significant preventive effects, which included preventing increases in levels of the proinflam-matory cytokine interleukin-12. The anti-allergic ingredients in TBW-ND were predicted to be highly complex compounds containing of polyphenols, polysaccharides and/or proteins. The results suggest pu-erh tea leaves could be a beneficial food for protecting against delayed-type allergy.

Anti-Obesity, Anti-Atherosclerotic and Anti-Oxidant Effects of Pu-Erh Tea on a High Fat Diet-Induced Obese Rat Model

Pu-erh tea, a traditional Chinese beverage, has been believed to have many benefits to human health and without side effects. In this study, we systematically analyzed the main active components of Pu-erh tea and investigated its anti-obesity, anti-atherosclerotic and anti-oxidant effects using an obese rat model. Obesity was induced by feeding a high-fat diet and subsequently the experimental obese mice were fed with high-fat diet supplemented with low (2.5%), medium (5%) or high (7.5%) doses of Pu-erh tea powder for 6 weeks respectively. As result, the body weight gain of the rats was decreased by medium and high doses of Pu-erh tea treatments. Furthermore, the levels of serum total cholesterol (TC), triglyceride (TG) and atherosclerosis index (AI) were significantly lowered by Pu-erh tea compared to the control group. Conversely, high density lipoproteincholesterol (HDL-C) level of the rats was significantly elevated by Pu-erh tea treatments. In addition, Pu-erh tea treatments increased the activities of anti-oxidative enzymes such as superoxide dismutase (SOD) and glutathione peroxides (GSH-Px), whereas reduced the level of lipid peroxidation product malondialdehyde (MDA) in obese rats. Collectively, our find-ings revealed that Pu-erh tea exerts comprehensive benefits in anti-obesity, anti-atherosclerotic and anti-oxidant effects, therefore can be used as a promising functional food in obesity management.

Discussion on the Sustainable Development of Pu'er Tea

The current situation of Pu'er tea in Yunnan was analyzed.The analysis result showed that the production output of Yunnan tea and the tea plantation area increased greatly when compared with the whole country,but the increase of Pu'er tea inclined to be stable.The restraining factors of Pu'er tea development were explored,and the corresponding countermeasures were put forward.It provided the basis for the sustainable development of Yunnan Pu'er tea.

The Story of Pu’er Tea Farmers in Yunnan

LISA See is the New York Times bestselling author of Snow Flower and the Secret Fan and many other popular books. Her new novel, The Tea Girl of Hummingbird Lane, soon topped the newspaper’s list of bestsellers after its publication in 2017 by Scribner Books and was reprinted in April 2018. More than 1,500 readers have written their reviews on the online platform of Amazon and Goodreads after reading the book.

Anomaly of the ionospheric electron density close to earthquakes:Case studies of Pu'er and Wenchuan earthquakes

The electron density recorded onboard the DEMETER satellite was analyzed to search for possible anomalies before earthquakes both in space and time. To distinguish pre-earthquake anomalies from the other anomalies related to geomagnetic activity, data were filtered using the Kp index. The analysis is based on the comparison of data recorded closely to earthquakes in space and time and past data for the same area. In analyzing data around the time and location of the Pu＇er and Wenchuan earthquakes, obvious anomalies in electron density were found close to the epicenters, and some remarkable disturbances were detected before the earthquakes occurred. The results were finally compared with those of previous works that used the same data but employed different analysis methods. Good agreement was found which suggests that these anomalies have a close relation to the earthquake preparation.

高效液相色谱法测定普洱熟茶中Puerins 401系列化合物的含量

文章建立了测定普洱熟茶中Puerins 401系列化合物含量的高效液相色谱分析方法。普洱熟茶中Puerins 401系列化合物用水提取,经二氯乙烷萃取,HP20自装柱富集净化,净化液经Waters Atlantis dC18色谱柱分离,以2 mmol/L乙酸铵水溶液(含1‰甲酸)和乙腈为流动相进行梯度洗脱,检测波长280 nm,流速1 mL/min,外标法定量。结果表明,在2.0~500.0 mg/L范围内,Puerins 401系列化合物线性关系良好,相关系数0.999。Puerins 401系列化合物最低检出限为3.6 mg/kg,最低定量限为11.9 mg/kg,加标回收率75.0%~99.5%,相对标准偏差均小于5%。该方法灵敏度高,准确性好,适用于普洱熟茶中Puerins 401系列化合物的测定。

普洱生茶和普洱熟茶多酚降脂作用比较研究进展

普洱茶及其多酚成分可通过抑制脂肪细胞分化、调节脂质代谢及改善肠道菌群等降低脂质积累和预防肥胖发生。普洱生茶和普洱熟茶具有不同的多酚成分,通过不同作用机制调节脂质代谢。比较普洱生茶和普洱熟茶多酚的降脂减肥功效及其作用机制,旨在为进一步研究普洱茶降脂功效提供参考。

基于普洱茶中重金属成分检测标准物质长期稳定性的研究

本文对所研发的普洱茶中重金属成分检测标准物质的长期稳定性进行了研究,阐述了该标准物质长期稳定性的研究理论及方法。该研究引用经典稳定性评估方案,采用电感耦合等离子体质谱方法,应用标准曲线分析规则(内标法),对普洱茶中Cr、Cu、Cd等重金属元素成分检测标准物质的长期稳定性进行了考察。结果表明:该实验可用于检验普洱茶中重金属成分检测标准物质的性能与品质。

2018年9月8日墨江5.9级地震云南普洱大寨流体异常特征及机理

文中梳理了2004年以来普洱大寨井连续观测的水化学离子和井-含水层渗透性异常特征。研究发现,在观测井周边250km范围内5.5级以上地震发生前,多次出现过可重复、可类比的异常变化,对地震具有较好的异常指示和预测意义。但相比以往震例,墨江5.9级地震发生前,无论是化学离子还是物理参数均出现了观测以来幅度最大的变化,异常状态较以往强烈很多,但发震的震级只有5.9级。为了研究这一现象产生的原因和机理,文中尝试从区域深部物质活动和区域应力水平2个方面对墨江5.9级地震前的异常演化过程开展讨论,得到以下认识:墨江5.9级地震前,流体异常整体呈现出较为显著的从深部到浅部、从背景到短期微观异常再到临震宏观异常的演化过程;墨江5.9级地震前,普洱大寨连续观测的水化学离子浓度异常和井-含水层渗透性的改变是由于区域内垂向剪切应力持续增强引起的含水层受挤压,从而形成了垂向的流体补给,最终引起不同含水层水体发生交替混合而产生的结果;本次异常形成初期还伴随深部物质剧烈活动的现象,较为显著的由深部到浅部的耦合作用过程可能是导致墨江5.9级地震前出现自观测以来地下流体异常幅度最显著的原因。因此,流体活动从深部开始,随着区域应力不断积累,不断向地表传递的演变过程是墨江5.9级地震前流体异常演化的本质特征;区域应力的作用方式和深部物质活动程度不同,是引起墨江5.9级地震前异常特征与研究区其他历史震例前明显不同的根本原因。文中研究为全面认识普洱大寨井地下流体异常的预测意义和地震前流体异常的深浅耦合演化过程提供了一定参考。

近红外光谱法快速测定晒青毛茶三种儿茶素组分含量

为了实现晒青毛茶儿茶素含量的快速检测,该研究利用高效液相色谱技术(High Performance Liquid Chromatography,HPLC)测定了50份晒青毛茶样品中的表没食子茶素没食子酸酯(Epigallocatechin Gallate,EGCG)、表没食子儿茶素(Epigallocatechin,EGC)、没食子酸(Gallic Acid,GA)三种儿茶素单体含量,结合样品的近红外光谱,分别建立了晒青毛茶三种儿茶素单体含量的偏最小二乘法(Partial Least Squares,PLS)模型,并对模型进行验证。实验结果表明,基于EGCG、EGC、GA含量所建立近红外模型的决定系数(Coefficient of Determination,R2)分别为99.99%、99.99%、99.92%;校正标准差(Root Mean Square Error of Calibration,RMSEC)分别为0.17、0.15、0.10;相对标准差(Relative Standard Deviation,RSD)分别为0.19%、0.27%、0.56%;外部验证的结果显示,三种儿茶素单体含量模型的预测值与真实值的平均绝对误差分别为0.13、0.12、0.07;平均相对误差分别为0.17、0.25、0.45。实验结果表明,该研究建立的近红外分析模型具有较高的预测准确度和稳定性,在快速检测晒青毛茶儿茶素方面具有潜在应用价值。

红曲霉与植物乳杆菌发酵普洱茶的抗氧化活性比较

该文探究添加红曲霉和植物乳杆菌发酵对普洱茶生化成分和抗氧化活性的影响。采用相关系数法分析主要生化成分和抗氧化指标的相关性。实验表明,六个发酵茶样的水浸出物、黄酮、茶多酚含量范围分别是50.64%~52.50%、0.77~0.95mg/g、13.21%~11.07%,单接植物乳杆菌R的茶多酚含量最高为13.21%。不同处理的茶样体外抗氧化能力存在显著差异(P<0.05),R的总抗氧化能力、DPPH自由基清除率和羟自由基清除率最高(10.36μgTrolox/mL、91.59%、29.43%)。相关性显示,茶红素、茶褐素与抗氧化能力呈负相关,但不显著;咖啡碱、茶多酚、茶黄素、总黄酮指标与抗氧化能力都有一定的显著相关性,其中茶多酚与总抗氧化能力、DPPH自由基清除率呈极显著相关(P<0.01),相关系数为0.74、0.95。添加菌种发酵的普洱茶具有较强抗氧化能力,且单菌种发酵普洱茶的抗氧化能力比混合发酵普洱茶的抗氧化能力更强,其中R的抗氧化能力最好。

普洱茶素Ⅴ~Ⅶ对4种乳腺癌细胞作用研究

普洱茶素(Puerins)是从普洱熟茶中分离得到的儿茶素衍生物,是一类结构独特的含氮多酚化合物。开展普洱茶素Ⅴ~Ⅶ抗乳腺癌细胞作用的研究,以4种不同受体表型的乳腺癌细胞株为模型,进行噻唑蓝(MTT)比色试验、蛋白质组学检测及细胞凋亡检测等试验。结果表明,普洱茶素Ⅴ、Ⅵ和Ⅶ等3个单体化合物对4种乳腺癌细胞都有显著的抑制作用;蛋白质组学分析发现,普洱茶素干预后乳腺癌细胞表达产生差异的蛋白主要集中于代谢通路,其次是癌症通路和黏附斑信号通路;细胞凋亡检测发现3个普洱茶素化合物均可诱导MDA-MB-231细胞的凋亡。本研究报道了普洱茶素Ⅴ~Ⅶ的抗乳腺癌细胞活性及初步作用机制,为研究普洱熟茶抗癌活性物质提供基础信息。

不同蒸压工艺下普洱茶抗氧化活性差异比较

目的探究不同蒸压工艺对普洱茶抗氧化活性的影响。方法本研究在普洱茶压制环节中设置不蒸压的原始样、蒸汽样、湿闷样、压饼打散样、压饼烘干样5种处理,采用分光光度法检测不同蒸压工艺下普洱茶总抗氧化能力、羟自由基清除能力、1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基清除率、超氧阴离子自由基清除能力并分析其差异。结果生茶总抗氧化能力压饼烘干样最大,显著高于湿闷样0.02 mol/L;生茶羟自由基清除能力湿闷样最高,显著高于原始样69.05 U/mL;生茶DPPH自由基清除率湿闷样最高,显著高于压饼打散样15.75%;生茶超氧阴离子自由基清除能力湿闷样最高,显著高于压饼打散样763.49 U/L。熟茶总抗氧化能力压饼烘干样最高,显著高于原始样0.07 mol/L;熟茶羟自由基清除能力湿闷样最高,显著高于原始样57.72 U/mL;熟茶DPPH自由基清除率湿闷样最高,显著高于原始样34.45%;熟茶超氧阴离子自由基清除能力压饼烘干样最高,显著高于压饼打散样1065.65 U/L。结论经过蒸压工艺中的压饼打散处理后,普洱生茶、普洱熟茶抗氧化活性降低,蒸汽、湿闷、压饼后烘干处理有利于其抗氧化活性提高,为普洱茶蒸压工艺的改进和抗氧化活性的提升提供理论基础。

基于响应面法优化沙棘普洱茶粉水提工艺及体外抗氧化能力评价研究

以沙棘普洱茶粉水提液中可溶性固形物为响应值,基于单因素及Box-Benhnken响应面法优化实验研究不同料液比、时间、温度、pH的影响.对不同原料配比下的沙棘普洱茶粉进行有效成分检测及体外抗氧化实验,分析、评价其体外抗氧化能力.得到沙棘普洱茶粉(沙棘叶∶普洱茶末=4∶1)的最优水提工艺条件为料液比(原料∶水)为1∶8(g/mL)、提取温度为79℃、提取时间为3 h、pH为8.3.沙棘普洱茶粉的活性成分含量较单一茶粉有所提高,对DPPH(2,2,-diphenyl-1-picrylhydrazyl)、ABTS(2,2′-azinobis(3-ethylbenzthiazoline-6-sulfonic acid)、CuPRAC(Cupric ReducingAntioxidant Power)及FRAP(Ferric Reducing Antioxidant Power)均具有较强的清除能力,制备的沙棘普洱茶粉均具有较好的体外抗氧化作用,为沙棘、普洱茶资源利用及功能性茶粉的开发提供一定参考.

普洱茶茶渣对茶花鸡2号肉品质的影响

试验旨在探讨饲粮中添加不同水平普洱茶茶渣对茶花鸡2号肉品质的影响。选取144只茶花鸡2号,随机分为3组,每组6个重复,每个重复8只。对照组饲喂基础饲粮,1%和2%茶渣组分别在基础饲粮上添加1%和2%的普洱茶茶渣,试验期28 d,试验结束进行鸡肉品质测定。结果表明:①与对照组相比,1%和2%茶渣组胸肌和腿肌肉品质物理特性(L^(*)值、a^(*)值、b^(*)值、pH4_(5min)、pH_(24h)、失水率、蒸煮损失率、剪切力)和常规营养成分(粗蛋白、粗脂肪和粗灰分含量)无显著差异(P>0.05),1%茶渣组胸肌各氨基酸含量以及2%茶渣组腿肌各氨基酸含量无显著差异(P>0.05)。②与对照组相比,2%茶渣组胸肌Asp、Thr、Ser、Glu、Ala、Cys、Val、Ile、Leu、Tyr、Lys、UAA和TAA含量极显著降低(P<0.01),Met、Phe、His、Arg、SAA、BAA、EAA和NEAA含量显著降低(P<0.05),Gly和Pro含量无显著变化(P>0.05),1%茶渣组腿肌Tyr含量极显著降低(P<0.01),Asp、Thr、Ser、Glu、Ala、Val、Ile、Leu、Phe、Lys、Arg、UAA、SAA、BAA、EAA、NEAA和TAA含量显著降低(P<0.05),Gly、Cys、Met、His和Pro含量无显著变化(P>0.05)。由此可见,饲粮中添加1%和2%普洱茶茶渣分别降低了茶花鸡2号腿肌和胸肌氨基酸含量,降低了肌肉风味。

接种酿酒酵母强化发酵普洱茶研究

为提高普洱茶的品质,将酿酒酵母(Saccharomyces cerevisiae)P002分不同阶段接种于晒青茶中进行强化发酵。结果表明,经第四翻强化接菌发酵后,感官审评时,香气、甜味和厚重感的数值增加,酸味数值降低;其茶多酚、茶褐素和可溶性糖含量显著高于传统自然发酵及其他阶段强化接菌发酵样(P<0.05),没食子儿茶素、儿茶素、表儿茶素、儿茶素没食子酸酯、花旗松素、杨梅素、木犀草素、山奈酚、鞣花酸、咖啡碱和茶碱的含量显著高于传统自然发酵(P<0.05)。真菌内转录间隔区(internal transcribed spacer,ITS)扩增子测序发现,在强化发酵中酵母目的相对丰度较自然发酵高,而散囊菌目、柔膜菌目和盘菌目的相对丰度较低。对照样的真菌菌落数最少,为4.9×10^(4)CFU/g,接入酵母菌后S1为7.8×10^(5)CFU/g。因此,接种酿酒酵母P002进行的强化发酵通过与其他微生物的协同作用改变普洱茶中茶叶的特征成分,从而提高普洱茶的感官品质。

富含植物乳杆菌的普洱熟茶品质分析

为开发一种感官品质优良且富含植物乳杆菌的普洱熟茶,将植物乳杆菌(Lactobacillus plantarum)PET003在自然发酵第20天时接种于茶样中,进行接菌强化发酵普洱熟茶。细菌16S rRNA扩增子测序发现,接菌强化发酵茶样中乳杆菌目(Lactobacillales)、微球菌目(Micrococcales)的相对丰度和植物乳杆菌属的DNA序列片段数较对照样品(未接种植物乳杆菌)增加。与对照样品比较,接菌发酵茶样中可溶性糖、茶褐素、茶多酚、咖啡碱、儿茶素、表儿茶素、没食子儿茶素、儿茶素没食子酸酯含量显著升高(P<0.05);感官审评发现接菌发酵茶样汤色红褐明亮,茶汤甜度和醇厚度增加。

普洱生茶贮藏过程中品质指标的规律变化分析

该研究选用贮藏时间在3~20年的18个普洱生茶茶样,通过感官审评和理化成分分析,探究贮藏过程中普洱生茶品质指标的规律变化。结果表明,随着贮藏时间增加,普洱生茶的汤色色泽逐渐加深,香气由清香转为陈香,滋味由醇厚转为醇和,叶底颜色变深变暗,贮藏10年及以上感官品质有所提升,但贮藏18年后,感官品质开始下降;水浸出物、咖啡碱、GC、C、CG的含量呈不规则变化,没食子酸含量逐渐增加,游离氨基酸、EGC、EC、EGCG、GCG、ECG的含量随着贮藏时间的增加呈下降趋势。对17个品质指标标准化后进行相关性分析、主成分分析和聚类分析,发现品质指标间存在显著相关性,通过系统聚类可将茶样分为5类,每间隔3~4年聚为一类,其中,A类综合得分最高,D类次之,E类最低,说明品质指标随着贮藏年份的增加呈现下降趋势,且在3~4年贮藏时间内保持稳定。该结果为深入研究普洱生茶贮藏过程中的品质变化提供依据。

不同方法渥堆发酵的普洱熟茶品质比较分析

为探究不同方式渥堆发酵的普洱熟茶品质差异,分别采用数控与传统两种发酵方法将茶叶加工成普洱熟茶样,分别对感官品质及主要理化成分进行相关性分析、主成分分析和聚类分析,探讨两种发酵方法普洱熟茶的品质差异。结果表明,数控设备发酵的普洱熟茶样感官品质整体低于传统方式发酵的普洱熟茶样,同时两种方法发酵的普洱熟茶各品质指标存在一定差异,品质指标间存在一定的相关性。数控设备发酵的普洱熟茶样和传统方式发酵的普洱熟茶样主要理化成分含量总体差异不大,除水分、咖啡碱和酚氨比差异显著(p<0.05),其他均不显著,但存在差异;主成分分析结果表明,传统方法渥堆发酵的普洱熟茶样综合品质优于数控发酵的普洱熟茶。试验结果可为普洱熟茶发酵技术的研究及普洱熟茶的加工生产提供理论依据。