The phenolic substances of manufactured tea. II. — Their origin as enzymic oxidation products in fermentation

Roberts, E. A. H.

doi:10.1002/jsfa.2740090405

Cited by 104 publications

(48 citation statements)

References 10 publications

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“…The so-called "fermentation" of black teas actually consists of enzymatic oxidation of native green tea polyphenols, catalyzed by polyphenoloxidase, followed by chemical reactions of the resulting quinones (18). A major part of tea leaf flavanols are thus converted into various types of products, including thearubigins and theaflavins, which are responsible for the characteristic dark brown color of black tea (20), and smaller quantities of theaflavic acids (21) and bisflavanols, which are also called theasinensins (22). The number of compounds is still increasing because new structures are regularly being identified (23)(24)(25), but no information is available on their respective concentrations in tea.…”

Section: Polyphenol Reactions In Food Processingmentioning

confidence: 99%

Polyphenols in foods are more complex than often thought

Cheynier

2005

The American Journal of Clinical Nutrition

634

399

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Polyphenols in foods are more complex than often thought [1][2][3] Véronique Cheynier ABSTRACT Dietary polyphenols show a great diversity of structures, ranging from rather simple molecules (monomers and oligomers) to polymers. Higher-molecular-weight structures (with molecular weights of 500) are usually designated as tannins, which refers to their ability to interact with proteins. Among them, condensed tannins (proanthocyanidins) are particularly important because of their wide distribution in plants and their contributions to major food qualities. All phenolic compounds are highly unstable and rapidly transformed into various reaction products when the plant cells are damaged (for instance, during food processing), thus adding to the complexity of dietary polyphenol composition. The polyphenol composition of plant-derived foods and beverages depends on that of the raw material used but also on the extraction process and subsequent biochemical and chemical reactions of plant polyphenols. The occurrence of specific tannin-like compounds (ie, thearubigins and theaflavins) arising from enzymatic oxidation is well documented in black tea. Various chemical reactions involving anthocyanins and/or flavanols have been demonstrated to occur during red wine aging. Current knowledge regarding the reaction mechanisms involved in some of these processes and the structures of the resulting products is reviewed. Their effects on organoleptic and nutritional quality are also discussed.Am J Clin Nutr 2005;81(suppl):223S-9S.

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Section: Polyphenol Reactions In Food Processingmentioning

confidence: 99%

Polyphenols in foods are more complex than often thought

Cheynier

2005

The American Journal of Clinical Nutrition

634

399

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“…SI TRs, SIa and SII TRs according to their solubility in different solvents. SI TRs are extractable into ethyl acetate, whereas SIa and SII TRs, which are those that remain in the aqueous phase, are more soluble in diethyl ether (Roberts, 1958). Division of TR into many groups makes the elucidation of individual TR components' contribution to tea quality difficult (McDowell et al, 1995).…”

Section: Determination Of Black Tea Samples Using a Taste-sensing Systemmentioning

confidence: 99%

Comparison of Phenolic Compounds and Taste of Chinese Black Tea

Wang¹,

Chen²,

Lin³

et al. 2014

FSTR

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“…There are thought to be two main pigment classes: the A broad picture of the chemical and biochemical theaflavins and the thearubigins. The theaflavins are processes involved in black tea fermentation has been benzotropolone compounds of known structure but the established by studies of the reactions of catechins in thearubigins are an inhomogeneous mixture of pigments enzymic model systems (Roberts 1958; Roberts and with molecular masses in the range 70CL400000 Da Myers 1959Myers , 1960Berkowitz et a/ 1971;Hilton 1972; (Roberts 1962;Sanderson 1972 1984). Much progress has been made using polyphenol…”

Section: Introductionmentioning

confidence: 99%

The chemical oxidation of catechins and other phenolics: A study of the formation of black tea pigments

1993

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Abstract:The chemical oxidation of polyphenols has been used to produce black tea pigments. (+)-Catechin, (-)-epicatechin, (-)-epicatechin gallate and (-)-epigallocatechin gallate were isolated from convenient sources, their identity being confirmed by mass spectrometry and HPLC. The oxidation of a mixture of (-)-epicatechin gallate and gallic acid gave an oxidation product of (-)-epicatechin gallate in addition to epitheaflavic acid 3-gallate. The catechins were oxidised chemically and the products analysed by HPLC, the chromatograms being compared with a black tea chromatogram. The reactions gave both resolved and unresolved pigments, and many of the resolved pigments had HPLC retention times close to black tea pigments. Each catechin behaved differently, the chromatograms of the oxidation products from each starting material being clearly distinguishable. Resolved pigments were obtained by the chemical oxidation of other phenolic compounds. This work provides a convenient method for studying the formation of resolved and unresolved black tea pigments.

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The phenolic substances of manufactured tea. II. — Their origin as enzymic oxidation products in fermentation

Cited by 104 publications

References 10 publications

Polyphenols in foods are more complex than often thought

Polyphenols in foods are more complex than often thought

Comparison of Phenolic Compounds and Taste of Chinese Black Tea

The chemical oxidation of catechins and other phenolics: A study of the formation of black tea pigments

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