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Titre du document / Document title

Total phenol, catechin, and caffeine contents of teas commonly consumed in the United Kingdom

Auteur(s) / Author(s)

KHOKHAR S. (1) ; MAGNUSDOTTIR S. G. M. (1) ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

(1) Procter Department of Food Science, University of Leeds, Leeds LS2 9JT, ROYAUME-UNI

Résumé / Abstract

Levels of total phenol, catechins, and caffeine in teas commonly consumed in the United Kingdom have been determined using reversed phase high-performance liquid chromatography. Tea bags or tea leaves were purchased from local supermarkets and extracted in boiling water for 5 min. The resulting data showed considerable variability in both total phenols [80.5-134.9 mg/g of dry matter (DM) in black teas and 87-106.2 mg/g of DM in green teas] and catechins (5.6-47.5, 51.5-84.3, and 8.5-13.9 mg/g of DM in black, green, and fruit teas, respectively); this was most probably a result of differing agronomic conditions, leaf age, and storage during and after transport, as well as the degree of fermentation. Caffeine contents of black teas (22-28 mg/g of DM) were significantly higher than in less fermented green teas (11-20 mg/g of DM). The relative concentration of the five major tea catechins ranked EGCG > ECG > EC > EGC > C. The estimated U.K. dietary intakes of total tea catechins, calculated on the basis of an average tea consumption of three cups of tea (200 mL cup, 1% tea leaves w/v), were 61.5, 92.7, and 405.5 mg/day from fruit teas, black teas, and green teas, respectively. The coefficients of variation were 19.4, 88.6, and 17.3%, respectively, indicating the wide variation in these intakes. The calculated caffeine intake ranged between 92 and 146 mg/day. In addition, many individuals will consume much larger quantities of tea, of various strengths (as determined by the brewing conditions employed). This broad spread of U.K. daily intakes further emphasizes the need for additional research to relate intake and effect in various population groups.

Revue / Journal Title

Journal of agricultural and food chemistry    ISSN  0021-8561   CODEN JAFCAU 

Source / Source

2002, vol. 50, no3, pp. 565-570 (24 ref.)

Langue / Language

Anglais

Editeur / Publisher

American Chemical Society, Washington, DC, ETATS-UNIS  (1953) (Revue)

Mots-clés anglais / English Keywords

Flavonoid

;

Stimulant plant

;

Environmental factor

;

Europe

;

Spermatophyta

;

Angiospermae

;

Dicotyledones

;

Theaceae

;

Public health

;

Daily dose

;

United Kingdom

;

Caffeine

;

Catechin

;

Phenol

;

Camellia sinensis

;

Fermentation

;

Plant leaf

;

Developmental stage

;

Storage

;

Comparative study

;

Black tea

;

Green tea

;

Chemical concentration

;

Chemical composition

;

Mots-clés français / French Keywords

Flavonoïde

;

Plante stimulante

;

Facteur milieu

;

Europe

;

Spermatophyta

;

Angiospermae

;

Dicotyledones

;

Theaceae

;

Santé publique

;

Dose journalière

;

Royaume Uni

;

Caféine

;

Catéchine

;

Phénol

;

Camellia sinensis

;

Fermentation

;

Feuille végétal

;

Stade développement

;

Stockage

;

Etude comparative

;

Thé noir

;

Thé vert

;

Concentration chimique

;

Composition chimique

;

Mots-clés espagnols / Spanish Keywords

Flavonoide

;

Planta estimulante

;

Factor medio

;

Europa

;

Spermatophyta

;

Angiospermae

;

Dicotyledones

;

Theaceae

;

Salud pública

;

Dosis diaria

;

Reino Unido

;

Cafeína

;

Catequina

;

Fenol

;

Camellia sinensis

;

Fermentación

;

Hoja vegetal

;

Grado desarrollo

;

Almacenamiento

;

Estudio comparativo

;

Té negro

;

Té verde

;

Concentración química

;

Composición química

;

Localisation / Location

INIST-CNRS, Cote INIST : 7332, 35400010009505.0260

Nº notice refdoc (ud4) : 13443161



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