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.

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.

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。

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.

La, Ce, Pr, Nd and Sm concentrations in Pu’er tea of Yunnan, China

The rare earth elements contents (La, Ce, Pr, Nd, Sm) in 150 Pu er tea samples were analyzed by using inductively coupled plasma atomic emission spectroscopy (ICP-AES), to evaluate the safety of Pu er tea. Among the investigated rare earth elements (REEs), Ce was the highest (35% of the total REEs content) whose concentrations were found to be in the range of 0.11–1.39 mg/kg, whereas that of Sm in the range 0.01–0.21 mg/kg, showing minimum levels (5.2%). La was the second highest element (28%) found in Pu e...

Pu’er raw tea extract alleviates DSS-induced colitis in mice by restoring intestinal barrier function and maintaining gut microbiota homeostasis

Numerous investigations have uncovered the outstanding therapeutic effect of tea extract on ulcerative colitis(UC).However,the therapeutic potential on UC of Pu’er raw tea extract(PRTE)remains debated and need to be investigated.In our study,PRTE(100 and 300 mg/kg)was applied to the DSS-induced colitis mice via intra-gastric administration.Results have shown that PRTE treatment significantly ameliorated DSS-induced weight loss,loose stool,hematochezia,colon atrophy,splenomegaly and colon pathological injury.It could also inhibit UC by down-regulating pro-inflammatory cytokines(IL-1β,IL-6 and TNF-α)and increasing the expression of tight junction protein(zonula occludens-1,ZO-1)to reinforce intestinal barrier.Fecal microbiota transplantation has further confirmed that PRTE could maintain intestinal homeostasis and relieve UC by improve the abundance of beneficial bacteria such as Lactobacillus,Muribaculum,Lachnospiraceae and Rikenellaceae,and reduce the abun-dance of harmful bacteria such as Turicibacter and Romboutsia.This study suggested that PRTE exhibited a noteworthy therapeutic effect on UC via restoring intestinal barrier function and maintaining gut microbiota homeostasis,which develops a safe and efficient novel strategy for UC prophylaxis and therapy,and provides theoretical support for medical application of Pu’er raw tea in the future.

Effects of different de-enzyming methods on microbial composition and volatile compounds of raw Pu’er tea based on microbiome and metabolomics

Microorganisms play a significant role in the quality formation of raw Pu’er tea,and volatile compounds mainly contribute to the aroma quality.However,different de-enzyming methods on the quality of raw Pu’er tea has not yet been reported.Microbiome and metabolomics were employed to comprehensively compare and analyze microbial community and volatile compounds in machine de-enzyming raw Pu’er tea(JS)and manual de-enzyming raw Pu’er tea(SS)in this study.High-throughput sequencing results showed that bacterial and fungal community compositions of JS and SS samples at phylum and genus levels were essentially identical,differed in relative abundance.A total of 65 and 71 volatile compounds were detected and characterized in JS and SS samples,respectively.Volatile components in JS and SS samples were mainly composed of alcohols,esters,aldehydes,alkanes,benzene and its derivatives,ketones,alkenes,phenols.A total of 88 differential volatile components between JS and SS samples were screened based on VIP>1 and p-value<0.05.Those results indicated that both microbial community composition and volatile compounds in raw Pu’er tea influenced by different de-enzyming methods.This work helps reveal the effect of different de-enzyming methods on the quality of raw Pu’er tea and provide a scientific reference basis for the improvement of raw Pu’er tea quality.

电子舌技术在普洱散茶等级评价中的应用

为了探讨茶叶的感官审评结果与电子舌测定结果的相关性,3个等级的云南普洱散茶分别被用于感官审评以及电位型电子舌的检测。电子舌测定结合主成分分析法(PCA)的结果显示,在第一和第二主成分的得分图上,电子舌可以区分特征十分相近的不同等级的普洱茶。同时对感官与仪器分析数据进行PCA分析后,找到了与不同等级茶叶感官品质相关性较高的传感器。因此,电子舌有望应用于茶叶生产的在线检测,以保证质量的一致性与分等分级的客观性。

茶氨酸和没食子酸在普洱茶中的含量变化

建立高效液相色谱分析茶氨酸和没食子酸的方法,对由云南大叶茶(Camellia sinensisvar.assamica)生产的晒青毛茶及其加工的普洱茶中二者的含量进行分析。结果表明,普洱茶中没食子酸的含量显著增高,而茶氨酸的含量则明显降低。茶氨酸和没食子酸的含量与原料的来源和质量,以及普洱茶的后发酵生产过程均有关系。对二者含量变化的机制进行了初步的讨论。

普洱茶多糖的提取工艺及抗氧化活性研究

用单因素实验研究茶多糖(TSP)提取工艺条件,并进一步通过连苯三酚自氧化测定所得普洱茶茶多糖的抗氧化活性。研究结果表明:普洱茶多糖的适宜提取条件为料液比1∶30、浸提温度70℃、浸提时间40min,提取次数4次,所得普洱茶多糖具有一定的抗氧化活性,其抗氧化活性与VC的抗氧化活性相近。

普洱茶的抗氧化活性研究进展

本文概述了近年来普洱茶抗氧化方面的研究进展,讨论了有待于进一步研究的内容,并与其他茶类进行比较分析,全面评价普洱茶作为特殊后发酵茶类的抗氧化活性,揭示不同发酵工艺所产生活性成分功效的差异性,为我国后发酵茶的保健作用机理研究提供一定的理论依据。

基于稀土元素含量的普洱茶产地识别研究

为了研究普洱茶产地识别技术,收集普洱茶三大主产区(西双版纳、普洱市、临沧市)的普洱生茶和普洱熟茶代表性样本共85个,采用等离子发射光谱质谱法(ICP/MS)测定了样本的16种稀土元素含量,并进行了主成分分析和逐步判别分析研究。结果表明,对3个地区的普洱生茶和普洱熟茶样本,分别进行线性判别分析的回判成功率和验证成功率都为100%。对3个地区的混合样本进行判别分析的回判成功率分别为93.3%、87.9%、90.9%,交叉验证的正确率分别为90%、87.9%、90.9%,18个外部验证样本的正确判别率为84.6%、81.4%、82.9%。本研究表明,通过稀土元素含量的线性判别分析,能够较好地区分三大主产区的普洱茶样品。

普洱茶热脱附—裂解色谱指纹图谱研究

采用热脱附/裂解色谱法测定不同制作工艺,不同存储时间,不同存放地点的普洱茶色谱指纹图谱,并选用模糊聚类数据处理手段对图谱进行综合分析,色谱图经过软件处理显得更直观精确;同时采用热脱附/裂解色谱-质谱对其裂解产物进行定性测定.各色谱峰调整保留时间的相对标准偏差RSD均≤2.73%,T的相对标准偏差RSD均≤11.54%.该工作为普洱茶的品质鉴定建立了一个快速、简便、科学的测试手段.使茶叶质量控制又迈进了新的一步.

普洱茶发酵过程中酶活性与主要品质成分关系初探

以云南大叶种晒青毛茶为原料,研究普洱茶渥堆发酵过程中主要酶类和品质成分的变化规律,并对其相互关系进行初步探讨。结果表明:发酵过程中,纤维素酶和果胶酶活性变化趋势相似,均在二翻时达到活性高峰,而且在产生微生物之前,纤维素酶和果胶酶已作为内源酶存在于茶叶中,而蛋白酶和多酚氧化酶是来源于微生物的外源酶;水浸出物、氨基酸、可溶性糖和茶多酚呈现不断减少的趋势,茶褐素呈现逐步增加的趋势,其中以多酚类物质变化最为明显。另外,研究表明:微生物分泌的胞外酶为茶叶中酚类物质的氧化、纤维素和果胶的分解、蛋白质的降解提供了有效的生化动力,使与茶叶品质形成相关的理化成分发生了复杂的变化。

滇青、青饼和普洱茶(熟饼)近红外指纹图谱分析

为深入了解滇青(晒青毛茶)、青饼和普洱茶(熟饼)在化学组成方面的异同,为茶类的区分与界别提供进一步的科学依据,对滇青、青饼和普洱茶(熟饼)的近红外化学指纹图谱采用欧氏距离、主成分分析和系统聚类等方法进行了定性判别分析。结果发现,普洱茶(熟饼)近红外指纹图谱与滇青、青饼图谱间的欧氏距离均大于各自组内最大偏差的绝对阈值,而滇青和青饼的组间差异小于各自的组内阈值;在第一主成分和第二主成分得分值散点图上,熟饼样品与青饼和滇青样品间界限分明,而滇青和青饼样品间无明显界限;所有的熟饼样品在系统聚类分析中聚为一类,而青饼与滇青样品聚为一类。因此,青饼的近红外光谱在各方面都与普洱茶(熟饼)样品差异显著,而与其原料滇青(晒青毛茶)十分接近。从化学本质上来说,青饼更接近于绿茶类产品。

曲霉属真菌在普洱茶后发酵中的作用

为阐明微生物在普洱茶后发酵过程中的作用及其机制,本文进行了普洱茶温湿度试验,并利用从普洱茶后发酵堆中分离鉴定的优势曲霉属真菌,进行接种试验和专用菌剂的发酵生产试验。结果提示,只有在微生物的作用下,普洱茶才具特有的感官特性,曲霉属真菌能控制后发酵的过程,改变茶叶的感官特性。曲霉属真菌的种类及组合对普洱熟茶的茶多酚组成与含量,以及没食子酸、茶氨酸、咖啡因等特征成分的含量均有显著的影响。因此,应用专用菌剂进行后发酵生产,能加快普洱茶的熟化速度,提高发酵成功率,保证产品质量的稳定性,使普洱熟茶的规范化生产成为可能。

普洱熟茶后发酵加工过程中曲霉菌的分离和鉴定

从云南省易武、基诺山、普洱和昆明后发酵加工生产的普洱熟茶堆中分离到7种曲霉菌,分别鉴定为:温特曲霉烟色变种,帚状曲霉,具黄曲霉,埃及曲霉,臭曲霉,日本曲霉原变种,以及局限灰曲霉。发现不同产地普洱熟茶中曲霉菌菌群的组成存在差异,对曲霉菌在普洱熟茶生产中的作用与意义进行了初步的讨论。

蜂蜜茉莉普洱茶饮料工艺的研究

研究了以普洱茶和茉莉花茶为主要原料制备的茶饮料的工艺流程。结果表明,浸提普洱茶和茉莉花茶的最佳工艺参数为:浸提时间15min,茶水质量比1:65,浸提温度85℃,浸提pH值为5.0,离心速度7000r/min,椴树蜜的添加量0.6%,VC的添加量为0.05%,饮料的糖度约为3.9°Bx,135℃瞬时灭菌5s。该饮料最大程度地保留了普洱茶和茉莉花茶的香味,又减少沉淀,茶汤色泽呈红色,澄清透明。

普洱速溶茶粉的制备工艺优化

为了提高普洱茶有效成分的提取,提高冲泡便捷性,本文采用加压热浸提法研究普洱茶多酚的最佳浸提工艺,将浸提液进一步干燥处理得到速溶茶粉,并对其进行感官分析及氨基酸和香气组分的分析。结果表明普洱茶多酚和水浸出物的最佳浸提条件为:温度130℃,时间30 min,压强0.185 MPa,料液比1∶25(g/m L),此条件下,普洱茶提取液中茶多酚含量为7.6%,水浸出物含量可达到30.3%。在最佳浸提条件下经过冻干后的茶粉冲泡液的滋味、香气和汤色与普洱原茶无显著差异。冻干处理的普洱茶浸提样中游离氨基酸总量比喷雾干燥样品中游离氨基酸含量高,且差异显著。不同干燥方式下的茶样香型特征差异较大,冻干对样品中的香气物质起到显著的保护作用。本文在茶叶香气滋味组分最大保留的前提下,为开发高氨基酸速溶茶,促进我国茶产业精深加工提供一定的理论依据。

普洱茶的香气成分

普洱茶（普洱熟茶）是以云南特有的大叶种茶制作的晒生毛茶（普洱生茶）为原料，经特殊的后李譬过程生产而成。与其原料晒青毛茶相比较，普洱茶的各类化学物质均发生了较大变化。本文应用气相色谱（GC）及气质联用（GC／MS／DS）技术，对云南临沧市生产的普洱茶和晒青毛茶等的香气成分进行分析比较。结果表明，普洱茶香气成分中的萜类、芳香族、以及有机酸类等化合物的组成和含量均与同一产地的晒青毛茶等均有显著的差异。