基于电子鼻气味指纹图谱快速鉴别茶籽油

以不同产地、不同类型、不同工艺和不同质量的茶籽油为研究对象，通过电子鼻技术获取茶籽油的风味信息，结合Loading负载分析、主成分分析（?principal component analysis，PCA）、线性判别分析（linear discriminant analysis，LDA）等对电子鼻传感器数据进行解读。通过欧氏距离（?euclidean distance，ED）、马氏距离（?markov distance，MD）和判别函数法(discriminant function method，DFA)对未知样品进行鉴别，以期建立不同茶籽油的快速、准确鉴别方法。结果表明：加工工艺极大地影响了茶籽油的气味差异，电子鼻响应值雷达图及Loading负载分析均表明W1S、W1W、W2S、W2W传感器对茶籽油样品具有较好的响应值，通过ED、MD、DFA可以识别不同类型和不同质量的茶籽油。基于PCA的LDA可以有效的鉴别不同类型的茶籽油，模型准确性高，其确定性大于99%。电子鼻技术结合化学计量学可以快速、有效鉴别不同的茶籽油并为茶籽油掺伪的快速鉴别提供了借鉴。     

基于挥发性成分定性判别风味油茶籽油掺伪浸出油茶籽油PCA模型和逻辑回归模型的对比分析

为了解决风味(原香和烤香)油茶籽油掺伪浸出油茶籽油的定性判别问题,设计高、低两个掺伪梯度,基于挥发性成分构建并对比分析了定性判别风味油茶籽油掺伪浸出油茶籽油的主成分分析(PCA)模型和逻辑回归模型。结果表明：逻辑回归模型定性判别风味油茶籽油掺伪浸出油茶籽油的能力较强,优于PCA模型;高掺伪梯度下定性判别原香和烤香油茶籽油掺伪浸出油茶籽油,PCA模型的最低检出限分别为20%和60%,而逻辑回归模型的最低检出限均为10%;低掺伪梯度下定性判别原香和烤香油茶籽油掺伪浸出油茶籽油,PCA模型的判别不准确,而逻辑回归模型的最低检出限均为4%。逻辑回归模型能很好地定性判别风味油茶籽油掺伪浸出油茶籽油。     

基于浸出茶油香气成分压榨茶油掺伪模型及应用

目的：解决压榨油茶籽油中掺入浸出油茶籽油的定量检测问题。方法：采用HS-SPME-GC-MS法对精炼浸出茶油和3种添加香精浸出茶油的关键香气成分进行测定和分析;将4种原香茶油和10种烤香茶油的香气成分相对含量与浸出茶油的香气成分相对含量进行对比,用浸出茶油中特有的香气成分作为特征数据进行Fisher判别分析,并建立LDA模型。结果：精炼浸出茶油中关键挥发性成分依次为(E)-2-癸烯醛、辛醛、(E)-2-壬烯醛和壬醛;3种添加香精的浸出茶油中特有的香精香气成分为2-甲氧基-3-甲基吡嗪、甲基环戊烯醇酮和2-甲基吡嗪。LDA模型对原香及烤香茶油的判别正确率分别达到84.0%和83.6%,能够鉴别原香及烤香茶油中掺伪比例为10%及以上的浸出茶油。结论：原香茶油的LDA模型能够很好地鉴别出添加茶油香精的浸出茶油,但烤香茶油的模型无法鉴别。     

GC—TOF MS结合化学计量学用于安化黑茶的识别

采用顶空固相微萃取联合气相色谱—飞行时间质谱(GC—TOF MS)对安化黑茶及其它产地黑茶中的挥发性成分进行检测,对41种共有挥发性组分进行定性定量分析。应用化学计量学统计工具对数据进行变量筛选、主成分分析法(PCA)和偏最小二乘判别分析(PLS-DA),筛选出安化黑茶的26个显著性差异香气成分,通过主成分得分投影图直观反映样本间的聚类趋势和分类信息,对安化黑茶与不同产地黑茶样品及其它种类茶叶进行有效区分和识别,找出14个对安化黑茶识别分类起着重要作用的挥发成分。结果表明,基于茶叶中挥发性成分差异的GC—TOF MS分析结合化学计量学统计方法用于安化黑茶识别是可行的。     

基于SPME-GC-MS和电子鼻分析方法分析薏仁饮料贮藏过程风味化合物变化

采用固相微萃取-气相色谱-质谱和电子鼻分析技术,通过相对气味活度值（relative odor activity value,ROAV）、主成分分析和聚类分析方法,对薏仁饮料保温贮藏过程中风味化合物、风味变化特征进行研究。结果表明：37?℃贮藏35?d,样品共检测出39?种主要的挥发性化合物,醛、醇、酮、烃、酯类化合物相对含量随贮藏时间延长而增加;贮藏期间ROAV不小于1的关键风味化合物有9?种,按贡献度大小依次为1-辛烯-3-醇、壬醛、3-甲基丁醛、己醛、辛醛、2-甲基丁醛、1-戊醇、辛醇、1-己醇;薏仁油脂氧化产生的醛、酮、酸和醇等挥发性化合物是薏仁饮料风味的主要成分;采用主成分分析及聚类分析能有效区分不同贮藏时间薏仁饮料,主成分分析显示样品贮藏初期和贮藏中后期的数据无重叠,其挥发性化合物存在差异,聚类分析结果将不同贮藏时间样品分为6?类,区分效果较好;通过主成分分析、ROAV和挥发性化合物相对含量变化,由此判定薏仁饮料贮藏期间品质劣变的特征性化合物为壬醛、己醛、辛醛、1-辛烯-3-醇。     

不同品种和花期茶树花挥发性物质的主成分和聚类分析

以四川小叶种（群体）、福鼎大白、福安大白、福选9号、金观音和梅占6 个茶树品种的花瓣露白和完全展开2 个花期的茶树花为研究对象,采用顶空固相微萃取-气相色谱-质谱法结合保留指数的方式对供试的12 个茶树花样品挥发性物质进行定性定量分析,并通过主成分和聚类分析对茶树花香型进行判定、区分和聚集。结果表明：气相色谱-质谱检测得到茶树花富含56 个挥发性物质;对56 个物质进行主成分分析可简化为6 个主成分,累积方差贡献率达85.55%,可反映样品的大部分信息;通过主成分和聚类分析将12 个茶树花样品分为2 类：花期Ⅰ和Ⅱ的梅占、花期Ⅱ的四川群体种、花期Ⅱ的金观音归为1 个集群;另8 个样品归为1 个集群。聚集在一起的茶树花样品香型相似,相似香型的茶树花可为原材料的混合采集及后期的生产加工提供参考。     

Quality identification and evaluation of Pu‐erh teas of different grade levels and various ages through sensory evaluation and instrumental analysis

To develop an objective, effective, flexible and cost‐saving method to assess Pu‐erh tea quality, Pu‐erh tea samples of different grade levels and various ages were analysed using sensory evaluation and various instrumental techniques, including chemical analysis and electronic tongue (ET). Results showed that taste profile analysis as a sensory evaluation method can meticulously describe and distinguish different Pu‐erh tea samples. Chemical analysis combined with hierarchical cluster analysis can cluster Pu‐erh ripened and raw tea both in compressed and scattered forms. However, no obvious variation tendency was observed in the chemical composition parameters of Pu‐erh tea of different grade levels or various ages. ET combined with principal components analysis (PCA) is effective in classifying Pu‐erh tea samples of different grade levels and various ages. ET followed by linear discriminant analysis (LDA) performs well in identifying Pu‐erh tea samples of various ages by establishing a discriminant model.     

庐山云雾茶挥发性成分主成分分析及产地判别

以顶空固相微萃取法结合气相色谱-质谱联用技术对3个不同产地庐山云雾茶挥发性成分进行测定。在庐山云雾茶样本中共鉴定出76种挥发性成分,其中相对含量较高的有顺-3-己烯-1-醇(4.00%)、庚醛(3.87%)、苄醇(13.76%)、十一烷(11.21%)、芳樟醇(3.70%)、苯乙醇(14.41%)、雪松醇(5.37%)等。利用主成分分析方法寻找影响挥发性成分的主要因子。结果表明,提取了6个主成分累计方差贡献率达到82.63%,3个不同产地的庐山云雾茶能通过各自的化学特征被完全区分开。市场上随机采集茶叶样本,采用同样的方法对其进行产地判别。结果可以从试样中鉴定出相同产地的庐山云雾茶,判别率为100%。     

单丛茶香气物质基础分析

采用茶叶感官审评及气相色谱-质谱等技术手段对香气成分进行检测,并结合多种统计分析方法,系统研究单丛茶香气化学品质的物质基础。结果表明：单丛茶最主要挥发性物质为吲哚、脱氢芳樟醇、芳樟醇、茉莉内酯、臧红花醛和β-环柠檬醛,其他重要挥发性物质为橙花叔醇、苯乙腈和α,4-二甲基-3-环己烯-1-乙醛等。在单丛茶挥发性组分中,以花果香为主的醇类化合物含量最多,含氮化合物含量次之。在相关分析与聚类分析中,银花香和桂花香表现较为独特。蜜香型和花香型单丛茶在主成分分析和正交偏最小二乘法判别分析结果中有较好分属区域,所建正交偏最小二乘法判别分析模型适用性和检验效果良好。该研究结果可为单丛茶的香气品质评价和提高产品质量提供科学依据。     

茶叶籽油研究进展

茶叶籽油从山茶科山茶属植物茶树的成熟种子中提取,富含不饱和脂肪酸和多种生理活性成分,可制成高级食用油、美容护肤品用油和医疗专用油,具有广阔的开发利用前景。本文综述了近年来茶叶籽油提取制备工艺、脂肪酸组成和含量分析、生理活性成分检测的研究进展,并针对生产实践中茶树结实率低、茶叶籽含油率中等两大问题,论述了改良茶园栽培管理技术增强茶叶籽丰产性、分子育种法提高茶叶籽含油率的可行性,旨在为制备优质的茶叶籽油提供参考。     

贵州不同产区代表绿茶的品质特征及香气组分分析

为了解贵州不同产区绿茶的品质差异及其主要香气组分,以贵州六大产茶区共12种代表性绿茶为原料,采用顶空-固相微萃取和气相色谱-质谱联用法（HS-SPME-GC-MS）分析其香气组成成分,结合化学成分分析、含量比较、香气活性值（OAV）、主成分分析共同筛选确定贵州绿茶的品质差异和主要贡献香气成分。结果表明:DB-17MS色谱柱与50/30 μm DVB/CAR/PDMS萃取头较为适合提取鉴定贵州绿茶的挥发性成分。12种贵州绿茶品质成分的平均含量为氨基酸4.37%、茶多酚16.81%、酚氨比3.88、水浸出物47.77%、可溶性糖3.19%、咖啡碱3.52%、总黄酮1.74%,体现贵州绿茶"嫩、鲜、浓、醇"特点。12种贵州绿茶共鉴定出75种香气物质,其中以碳氢化合物和醇类居多。结合PCA、OAV和含量比较3种方式筛选出31种香气成分是贵州绿茶显花香、果香、清香和栗香味的主要成因。黔南和黔中绿茶呈浓郁花果香的主要贡献成分有苄醇、茉莉酮、苯乙醇;金合欢烯等为黔北绿茶增添清甜香气特征;3-蒈烯使黔东南绿茶带松木香特征;2-哌啶酮、D-毕澄茄烯、水杨酸甲酯等使黔西南和黔西绿茶呈现香樟味、冬青油味特征。     

A study on chemical estimation of pu‐erh tea quality

Chemical compositions and infusion colour differences of seven pu‐erh tea samples and their correlation to sensory quality were investigated. The results showed that the pu‐erh tea contained 37.1 mg g^?1 caffeine, 15.7 mg g^?1 amino acids, 67.0 mg g^?1 polyphenols and 8.41 mg g^?1 total catechins, on average. Among the 17 tested volatile compounds, n‐valeraldehyde was not detected. The most abundant volatile was β‐ionone and the next was linalool oxide II. Infusion colour analysis showed that the pu‐erh tea had deep hue with ΔE ranging from 66.8 to 79.2. Spearman's linear correlation analysis showed that total quality score (TQS) of the pu‐erh tea was significantly correlated to concentration of amino acids, linalool oxide II and infusion colour indicator ΔE. Five components were extracted from the 34 tested indicators by principal component analysis and were regressed on the TQS to produce six Pearson's linear regression equations for estimating sensory quality of pu‐erh tea, among which two were statistically significant, ie TQS = 57.47 ? 0.18geraniol + 0.33polyphenols ? 1.14n‐caproaldehyde ? 1.38linalool oxide I + 0.21caffeine (p < 0.01) and TQS = 57.42‐0.03Citral + 0.33polyphenols ? 1.14n ? caproaldehyde ? 1.40linalool oxide I + 0.20caffeine (p < 0.01). Copyright © 2004 Society of Chemical Industry     

基于GC-IMS对勐海县晒青毛茶的挥发性组分分析

为探索云南省勐海县主产茶区的晒青毛茶的挥发性有机物特征，比较各乡镇茶叶之间的差异，本文运用GC-IMS技术对勐海县布朗山乡、勐宋乡、格朗和乡，每个乡镇4份样品，共计12份勐海大叶种晒青毛茶样品进行挥发性有机物检测和分析。PCA分析结果表明:12份样品可以分为两大组，布朗山乡的曼囡新寨茶（4号茶样）、勐宋乡的曼迈茶（8号茶样）、格朗和乡的南糯新路茶（10号茶样）为B组，剩余九份样品为A组。指纹图谱结果表明:B组的3份茶样的挥发性组分较相似，醛类、酯类含量均较高。A组样品中，布朗山乡的曼囡道坎茶（2号茶样）的醛类、酮类、酯类、醇类、烯类挥发性有机物组分种类和含量均较高，而格朗和乡的南糯石头一队茶（11号茶样）的酯类物质非常丰富。综上分析，勐海地区3个乡镇的晒青毛茶在挥发性有机物组分上没有明显的乡镇聚集性，每个产区的晒青毛茶样都有各自的特征性挥发组分，布朗山乡的道坎茶（2号茶样）丰富的挥发性物质为优质晒青毛茶原料的选取提供了新方向，同时勐宋乡的曼囡河边寨茶（5号茶样）、格朗和乡的南糯石头一队茶（11号茶样）特殊的挥发性组分为晒青毛茶的拼配提供了依据。此外，本实验也说明GC-IMS技术用于茶叶样品挥发性有机组分的快速定性分析具有良好的可行性。     

云南晒青红茶与烘青红茶香气成分对比

采用顶空固相微萃取（headspace solid-phase microextraction,HS-SPME）结合气相色谱-质谱（gaschromatography-mass spectrometry,GC-MS）分析3 种晒青红茶和3 种烘青红茶的香气成分,并利用主成分分析（principal component analysis,PCA）和聚类分析（clustering analysis,CA）找出这2 种不同干燥方式红茶的异同点,以实现对它们的区分。结果表明,2 种红茶中一共鉴定出香气成分76 种,香气成分主要以醇类、酮类和酯类化合物为主,其中醇类化合物相对含量在晒青红茶和烘青红茶中分别占57.43%和60.45%,主要包括芳樟醇、芳樟醇氧化物、香叶醇和橙花叔醇等萜烯醇类物质。通过对比发现,晒青红茶和烘青红茶在香气成分的组成及相对含量上存在较高程度的相似性。但通过使用PCA和CA,晒青红茶和烘青红茶之间能实现较好的区分,说明不同的干燥方式对这2 种红茶的香气成分有一定的影响。因此,通过结合晒青红茶和烘青红茶的香气成分及相对含量,HSSPME-GC-MS结合多元统计学方法能够实现2 种不同干燥方式红茶的区分。     

茶叶籽油与油茶籽油的成分比较研究

采用气相色谱/质谱联用仪对茶叶籽油和油茶籽油的成分进行检测分析.结果表明:两种油均检测出21种成分,主要成分相同;茶叶籽油中含9-羰基壬酸,油茶籽油含芥酸,可用以鉴别;茶叶籽油和油茶籽油中油酸含量分别为78.377%.73.201%,亚油酸含量分别为3.287%,4.170%.     

基于HS-SPME-GC-MS和OAV鉴定浮梁红茶关键呈香物质

为探讨浮梁红茶的挥发性香气成分组成,从中筛选其关键呈香物质.本研究采用顶空固相微萃取-气质联用(headspace-solid phase microextraction-gas chromatography-mass spectrometry,HS-SPME-GC-MS)鉴定浮梁红茶的挥发性成分,通过香气活度值(od...     

HS‐SPME/GC‐MS and chemometrics for volatile composition of Chinese traditional aromatic vinegar in the Zhenjiang region

The main purpose of this study was to determine the volatile composition of Zhenjiang aromatic vinegar, one of the four famous China‐style cereal vinegars, by using headspace solid‐phase microextraction (HS‐SPME)/gas chromatography‐mass spectrum (GC‐MS) and chemometrics. For this purpose, the HS‐SPME sampling method for the volatile compounds of Zhenjiang aromatic vinegar was optimized by a second‐order rotatable central composite experimental design (CCD). A HS extraction of the volatile compounds by incubation on a 65 µm thickness polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre during 44.2 min at 69.5°C with 1.9 g NaCl add gave the most effective and accurate extraction. By the optimized method, a total of 58 volatile compounds, including 9 alcohols, 13 acids, 16 esters, 5 aldehydes, 4 ketones and 8 heterocycle compounds, were identified from 13 aromatic vinegar samples manufactured in Zhenjiang region. By principal components analysis (PCA), the thirteen vinegar samples were classified into 3 groups, and 10 volatile compounds were chosen as characteristic compounds of Zhenjiang aromatic vinegars. Copyright © 2012 The Institute of Brewing & Distilling     

Analysis of tea catechins in vegetable oils by high‐performance liquid chromatography combined with liquid–liquid extraction

In this study, a method was developed for the determination of various tea catechins in vegetable oils. Firstly, vegetable oils including tea seed oil, sunflower seed oil and soya bean oil were extracted by methanol/water (40:60, v/v), and then, a high‐performance liquid chromatography (HPLC) method was developed for the simultaneous determination of GA, caffeine, EGC, EGCG, EC, ECG, GC, GCG, C and CG. For the compounds detected in tested vegetable oils, LODs were in the range of 0.05–1.65 ng, both intraday and interday relative standard deviations (RSDs) were <5.0%, and the recovery rates were in the range of 96.2–100.5% with RSD <3.7%. The results showed in vegetable oils which declared to had added tea catechins in, the concentrations of tea catechins were less than that showed in package label, and the content of EGCG was the highest in all samples. Therefore, the advancement made in our study will facilitate studies of tea catechins in oil industry.     

Analysis of characteristic aroma of fungal fermented Fuzhuan brick‐tea by gas chromatography/mass spectrophotometry

Fuzhuan brick‐tea is a popular fermented Chinese dark tea because of its typical fungal aroma. Fungal growth during the production process is the key step in achieving the unique colour, aroma and taste of Fuzhuan brick‐tea. To further understand the generation of the characteristic aroma, changes in the main volatile compounds of Fuzhuan brick‐tea during the fungal growth stage were studied by gas chromatography/mass spectrophotometry. The results showed that the content of volatile compounds, especially aldehyde compounds with stale aroma such as (E)‐2‐pentenal, (E)‐2‐hexenal, 1‐penten‐3‐ol, (E, E)‐2,4‐heptadienal and (E, Z)‐2,4‐heptadienal, increased significantly in fermented tea samples. The concentration of terpene alcohols with flower aroma also increased notably during the fermentation process. The compounds with stale and flower aromas in combination with some volatile components of the raw material contributed to the characteristic ‘fungal/flower’ aroma of Fuzhuan brick‐tea. Microbial metabolism during the fermentation process probably played the key role in the generation of characteristic aromatic compounds of Fuzhuan brick‐tea. Copyright © 2007 Society of Chemical Industry