Black Tea Aroma Research Articles

Effects of Production Locations and Plucking Intervals on Clonal Tea Fatty Acids Levels in the Kenya Higlands

Tea leaves contain unsaturated fatty acids which are precursors of aroma compounds. Despite uniform plucking practices in Kenya, plain black tea quality varies with locations. Variations in tea aroma and/or precursors with production area have not been established in a single cultivar under same agronomic input at different locations. Trials were conducted in five locations using clone BBK 35, harvested at varying intervals. The fatty acids varied (P ≤ 0.05) with locations and increased (P ≤ 0.05) with long plucking intervals, demonstrating leaf of same standard plucked at varying intervals contains different levels of fatty acids even in one location. The different increase rates in various locations might be in part the reason of the differences in aroma of black tea from different locations even when agronomic inputs are similar. Results demonstrate that harvesting at shorter intervals and developing region-specific plucking policies may improve tea quality.

Electronic nose for black tea quality evaluation by an incremental RBF network

Black Tea is conventionally tested by human sensory panel called “Tea Tasters”, who assign quality scores to different teas. Electronic nose-based studies aimed at co-relation of sensor array output signature with Tea Tasters’ scores have already been accomplished by the authors with good accuracy [N. Bhattacharyya, R. Bandyopadhyay, M. Bhuyan, B. Tudu, D. Ghosh, A. Jana, Electronic nose for black tea classification and correlation of measurements with “Tea Taster” marks, IEEE Trans. Instrum. Meas. 57 (2008) 1313–1321], where a number of conventional neural network topologies have been explored. One of the principal problems encountered in the above studies is collection of tea samples as tea industries in India are spread over dispersed locations and quality of tea varies considerably on agro-climatic condition, type of plantation, season of flush and method of manufacturing. As a result, the entire dataset is not available at a time and training the conventional neural network models becomes difficult. In this regard, classifiers having the incremental learning ability can be of great benefit by automatically including the newly presented patterns in the training dataset without affecting class integrity of the previously trained system. In the presented paper, the radial basis function (RBF) neural network with the incremental learning feature is used in the pattern recognition algorithm for black tea aroma classification with electronic nose.

Analysis of glycosidically bound aroma precursors in tea leaves. 2. Changes in glycoside contents and glycosidase activities in tea leaves during the black tea manufacturing process.

Glycosides are known to be precursors of the alcoholic aroma compounds of black tea. They are hydrolyzed by endogenous glycosidases during the manufacturing process. Changes in the amounts of these glycosides during the manufacturing process were investigated by using a capillary gas chromatographic--mass spectrometric analysis after trifluoroacetyl derivatization of the tea glycosidic fractions. Primeverosides were 3-fold more abundant than glucosides in fresh leaves, but they decreased greatly during the manufacturing process, especially during the stage of rolling. After the final stage of fermentation, primeverosides had almost disappeared, whereas glucosides were substantially unchanged. These results show that hydrolysis of the glycosides mainly occurred during the stage of rolling and confirm that primeverosides are the main black tea aroma precursors. This was also supported by the changes in the glycosidase activities in tea leaves. The glycosidase activities remained at a high level during withering but decreased drastically after rolling.

Green tea composition, consumption, and polyphenol chemistry

Tea is grown in about 30 countries but is consumed worldwide, although at greatly varying levels. It is the most widely consumed beverage aside from water with a per capita worldwide consumption of approximately 0.12 liter per year. Tea is manufactured in three basic forms. Green tea is prepared in such a way as to preclude the oxidation of green leaf polyphenols. During black tea production oxidation is promoted so that most of these substances are oxidized. Oolong tea is a partially oxidized product. Of the approximately 2.5 million metric tons of dried tea manufactured, only 20% is green tea and less than 2% is oolong tea. Green tea is consumed primarily in China, Japan, and a few countries in North Africa and the Middle East. Fresh tea leaf is unusually rich in the flavanol group of polyphenols known as catechins which may constitute up to 30% of the dry leaf weight. Other polyphenols include flavonols and their glycosides, and depsides such as chlorogenic acid, coumarylquinic acid, and one unique to tea, theogallin (3-galloylquinic acid). Caffeine is present at an average level of 3% along with very small amounts of the other common methylxanthines, theobromine and theophylline. The amino acid theanine (5-Nethylglutamine) is also unique to tea. Tea accumulates aluminum and manganese. In addition to the normal complement of plant cell enzymes, tea leaf contains an active polyphenol oxidase which catalyzes the aerobic oxidation of the catechins when the leaf cell structure is disrupted during black tea manufacture. The various quinones produced by the enzymatic oxidations undergo condensation reactions which result in a series of compounds, including bisflavanols, theaflavins, epitheaflavic acids, and thearubigens, which impart the characteristic taste and color properties of black tea. Most of these compounds readily form complexes with caffeine. There is no tannic acid in tea. Thearubigens constitute the largest mass of the extractable matter in black tea but their composition is not well known. Proanthocyanidins make up part of the complex. Tea peroxidase may be involved in their generation. The catechin quinones also initiate the formation of many of the hundreds of volatile compounds found in the black tea aroma fraction. Green tea composition is very similar to that of the fresh leaf except for a few enzymatically catalyzed changes which occur extremely rapidly following plucking. New volatile substances are produced during the drying stage. Oolong tea is intermediate in composition between green and black teas.

Chirospecific analysis in flavor and essential oil chemistry Part B. Direct enantiomer resolution of frans-?-ionone and trans-?-damascone by inclusion gas chromatography

The direct capillary gas Chromatographic separation oftrans-α-ionone andtrans-α-damascone enantiomers is reported using heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin in polysiloxane as a suitable chiral stationary phase. The method described has been applied to determine the naturally occurring enantiomeric composition oftrans-α-ionone in the absolutes of the flowers ofBoronia megastigma Nees andOsmanthus fragrance Lour., Costus root oil (Saussurea lappa Clarke) as well as in odor concentrates of violet flowers (Viola odorata L.), fresh raspberries, carrots and vanilla pods. Furthermore, the optical purity oftrans-α-ionone in the solvent extracts of distilled alcoholic raspberry beverage, raspberry fruit juice concentrate and black tea was investigated.Trans-α-ionone was either isolated by headspace stripping in vacuo or by organic solvent extraction and subsequently enriched by multidimensional preparative Chromatographic techniques.Trans-α-damascone was isolated from Virginia tobacco extract and from black tea aroma and was enriched for direct chirospecific analysis by medium pressure liquid chromatography followed by multidimensional preparative capillary gas chromatography. The importance of chirality as an essential criterion for the discrimination of natural and nature-identical aromas is discussed briefly.

Variations in the leaf standard, chemical composition and quality of black tea (Camellia sinensis) due to plucking intervals

AbstractGreen leaf standard, chemical composition and quality of black tea (Camellia sinensis (L) O Kuntze) change with plucking intervals. Long plucking intervals lead to poor leaf standard with a lot of mature leaves and lower theaflavins, the sum of volatile flavour compounds imparting a sweet flowery aroma (group II volatile flavour compounds), caffeine contents and tasters' evaluations of black tea. The sum of volatile flavour compounds imparting inferior, grassy, green flavour (group I volatile flavour compounds) to tea, however, increases with long plucking intervals.

Aroma of black tea. Preparation of a tea concentrate by reverse osmosis and its analytical characterization

Zwei Celluloseacetat-Membranen unterschiedlichen Ruckhaltevermogens (RO 2 und RO 2/1) sind zur Herstellung von Konzentraten mittels Umkehrosmose aus wasserigen Auszugen der Tee-qualitaten Indian Broken (1B) und Darjeeling Orange Pekoe (DOP) eingesetzt worden. Wahrend in der Versuchsreihe mit der IB-Qualitat infolge Verblockung der Membran RO 2 Storungen auftraten, verlief die Konzentrierung mit der DOP-Qualitat und der Membran RO 2/1 storungsfrei: Konzentrierfaktoren bis zu 6,5 fur Extrakt, Phenol- und Coffeinanteil sind erreicht worden. Bezuglich der Aromastoff-Konzentrierung wurden stoffspezifisch unterschiedliche Ergebnisse erhalten: Nur fur „Terpenoxide” und Terpenalkohole sind hohe Anreicherungen beobachtet worden, wahrend bei anderen Stoffklassen, wie z. B. Terpenkohlenwasserstoffen und Estern deutliche Permeatverluste auftraten. Die Wiederfindungsraten lagen bei Alkanalen und Alkenalen lediglich bei 25%. Beide Membrantypen zeigten im ubrigen hohe Spezifitat im Ruckhaltevermogen basischer Verbindungen.

Additional volatiles of black tea aroma

Additional volatiles of black tea aroma

Extraction, purification, and partial characterization of a tea metalloprotein and its role in the formation of black tea aroma constituents.

Extraction, purification, and partial characterization of a tea metalloprotein and its role in the formation of black tea aroma constituents.

New volatile constituents of black tea aroma

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNew volatile constituents of black tea aromaOtto G. Vitzthum, Peter. Werkhoff, and Peter. HubertCite this: J. Agric. Food Chem. 1975, 23, 5, 999–1003Publication Date (Print):May 1, 1975Publication History Published online1 May 2002Published inissue 1 May 1975https://doi.org/10.1021/jf60201a032RIGHTS & PERMISSIONSArticle Views511Altmetric-Citations60LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (436 KB) Get e-Alerts Get e-Alerts

An Investigation of the Tea Aroma. Part I. New volatile black tea constituents

AbstractA total of 68 constitutents, mainly aldehydes, ketones and esters, have been identified for the first time in a black tea aroma concentrate using coupled gas‐chromatography/mass spectrometry.

Sur la composition de l'arôme de Thé noir IV

Abstract17 substances were shown to be present in the aroma of black tea. This brings the total number of substances now identified to 187. Many of these new aromatic constituents are present only in traces. Nevertheless they possess an appreciable olfactive intensity whose flowery and/or fruity characteristics are found in many perfumed black teas such as: Kenya, Darjeeling, Ceylan, China and Oolong.The components were identified by GC/MS. and their presence in the aroma verified by GC.

Sur la composition de l'arǒme de the noir V

AbstractMethyl anthranilate, geranylacetone and five lactones: γ‐valerolactone, γ‐heptalactone, γ‐décalactone, δ‐décalactone, 5‐hydroxy dec‐7‐enoic acid‐lactone have recently been identified in black tea aroma by means of GC./MS. and by sniffing the effluent from a gas chromatograph. Their intrinsic character, rather fruity and flowery, gives a certain freshness and an agreable note to the aroma.

Nouvelle Synthèse de l'α-Damascone

A new synthesis of α-damascone (a black tea aroma constituent having a powerful fragrance) was described.

Formation of black tea aroma

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFormation of black tea aromaGary W. Sanderson and Harold N. GrahammCite this: J. Agric. Food Chem. 1973, 21, 4, 576–585Publication Date (Print):July 1, 1973Publication History Published online1 May 2002Published inissue 1 July 1973https://doi.org/10.1021/jf60188a007RIGHTS & PERMISSIONSArticle Views1190Altmetric-Citations103LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts

Gas chromatographic-mass spectrometric analyses of “flavory” and “non-flavory” ceylon black tea aroma concentrates prepared by two different methods

Aroma concentrates of Ceylon black tea were prepared by two methods, (1) steam distillation and (2) adsorption of charcoal of the head-space vapor over a tea brew followed by elution with diethyl ether. The former method was superior to the latter, perhaps partly due to formation or artefacts on the charcoal. Comparison by gas chromatography of aroma concentrates from “flavory” and “non-flavory” tea showed marked qualitative and quantitative variations in the components detected. Twenty-one of these components were identified by mass spectometry.

A Research Note BIOCHEMISTRY OF TEA FERMENTATION: FORMATION OF t‐2‐HEXENAL FROM LINOLENIC ACID

U‐14C‐Linolenic was shown to be transformed in part to t‐2‐hexenal during the conversion of fresh tea leaf to black tea. In fact, t‐2‐hexenal was the only volatile compound which was formed during the conversion process. Further, the formation of t‐2‐hexenal was shown to be dependent on the enzymic conversion process since no t‐2‐hexenal was formed when the leaf enzymes were inactivated prior to adding the 14C–linolenic acid. Since linolenic acid is the major fatty acid present in fresh tea leaf and t‐2‐hexenal is a prominent component of black tea aroma, it must be concluded that this reaction helps to determine the character of black tea aroma.

Constituents and Composition of Steam Volatile Aroma from Ceylon Tea

The constituents of steam volatile aroma, which were responsible for topnote of Ceylon tea aroma, were identified. A total of 57 compounds were identified, of which 10 (ter-pinolene, n-nonanal, trans-2-pentenal, trans-3-octen-2-one, 6-methyl-3,5-heptadien-2-one, n-nonanol, cis-3-hexenylbutyrate, cis-3-hexenylcaproate, α-terpinylacetate and nerylacetate) had not previously been reported as associated with aroma of black tea. Approximate composition of topnote aroma from Ceylon flavory tea was also determined.

Constituents and Composition of Steam Volatile Aroma from Ceylon Tea

The constituents of steam volatile aroma, which were responsible for topnote of Ceylon tea aroma, were identified. A total of 57 compounds were identified, of which 10 (ter-pinolene, n-nonanal, trans-2-pentenal, trans-3-octen-2-one, 6-methyl-3,5-heptadien-2-one, n-nonanol, cis-3-hexenylbutyrate, cis-3-hexenylcaproate, α-terpinylacetate and nerylacetate) had not previously been reported as associated with aroma of black tea. Approximate composition of topnote aroma from Ceylon flavory tea was also determined.

BIOCHEMISTRY OF TEA FERMENTATION: THE ROLE OF CAROTENES IN BLACK TEA AROMA FORMATION

ABSTRACT— The carotenoid compounds present in fresh tea leaf were quantitatively extracted and separated by thin layer chromatography. Neoxanthin. Neoxanthin, violaxanthin, lutein, and β‐carotene were identified and estimated by spectrophotometry. Quantitative studies showed that these carotenoid compounds decreased from about 0.053% (dry weight basis) in the fresh tea leaf to about 0.030% in the fermented (3 hr fermentation) leaf to about 0.026% in the fired black tea. This analytical study was followed by an investigation to determine how, and to what, these carotenoid compounds are altered during the black tea manufacturing process. The fate of β‐carotene in tea fermentation was first studied in model systems. The model consisted of a crude soluble enzymes preparation extracted from fresh tea leaves, tea flavanols, and β‐carotene. The model system was buffered at pH 5.4 and incubated for 30 min at 30°C. The volatile compounds formed in this system were studied by gas chromatographic analysis of headspace volatiles. It was found that β‐ionone (identified by GLC retention time and mass spectrometry) was formed in this model tea fermentation system as a result of tea flavanol oxidation and drying of the reaction mixture after oxidation. Further, it was found that all three basic reaction mixture ingredients, i.e., active tea enzymes preparation, tea flavanol, and β‐carotene were necessary for the production of β‐ionone. While β‐ionone was the major volatile product formed from β‐carotene in these systems, experiments utilizing 15,15′.14C‐β‐carotene showed that several unidentified compounds also were formed. The formation of β‐ionone from β‐carotene during black tea manufacture was confirmed in separate experiments. Organoleptic and GLC headspace analyses showed that black teas made in the usual way except that β‐carotene was added at the leaf maceration stage (stage which initiates fermentation) contained more β‐ionone than control black teas. The results obtained with β‐carotene have been generalized on paper for all of the carotenoid compounds known to be present in fresh tea leaf. The results of this work indicate that many of the important black tea aroma constituents are probably formed during the tea conversion process by oxidative degradation of the carotenoid compounds present in the system. The possible mechanism for these transformations is discussed.