Factors Affecting the Caffeine and Polyphenol Contents of Black and Green Tea Infusions

Abstract

The effects of product and preparation variables on the in-cup chemical composition of tea extracts is of interest because the appearance and taste characteristics and the possible health effects of a tea liquor arise from the chemical components extracted from the leaf during tea preparation. A comprehensive study was therefore undertaken to determine the contributions of product and preparation variables on the total soluble solids, caffeine, and polyphenol contents of tea extracts. The results of this study show that the variety, growing environment, manufacturing conditions, and grade (particle size) of the tea leaves each influence the tea leaf and final infusion compositions. In addition, the composition of the tea infusion was shown to be influenced by whether the tea was contained in a teabag and, if so, the size and material of construction of the bag. Finally, the preparation method, including the amounts of tea and water used, infusion time, and amount of agitation, was shown to be a major determinant of the component concentrations of tea beverages as consumed. An illustration of the variation introduced by these product and preparation factors is provided by comparing solids, caffeine, and polyphenol contents of green and black tea infusions when commercial products are prepared according to the instructions given on their packaging.

Effects of Infusion Time and Addition of Milk on Content and Absorption of Polyphenols from Black Tea

“…The observed effects of increasing total phenols and antioxidant concentrations with increasing infusion time are also known to be influenced by stirring duration and intensity, leaf size, and tea bag porosity (30,32). Taken together, these observations re-emphasize the importance of gathering brewing and preparation details in addition to numbers of cups consumed when associations (9) or semiskimmed milk (9) to tea infusions (3 g/300 mL).…”

Chá verde brasileiro (Camellia sinensis var assamica): efeitos do tempo de infusão, acondicionamento da erva e forma de preparo sobre a eficiência de extração dos bioativos e sobre a estabilidade da bebida

“…Os maiores produtores de Camellia sinensis são a China e a Índia e os chás provenientes desses países já foram objeto de muitos estudos (ASTILL et al, 2001;FERNANDEZ et al, 2002;LIN et al, 2003;PERVA-UZUNALIC et al, 2006). O cultivo do chá verde é hoje, entretanto, realizado em diversos países em praticamente todos os continentes (CHAN;LIM;CHEW, 2007;YAO et al, 2005).…”

“…A agitação das misturas favoreceu a extração tanto para o chá a granel quanto para o chá acondicionado em sachês. Resultados semelhantes foram obtidos em estudo utilizando chá verde de procedência chinesa (ASTILL et al, 2001). Na Figura 1, é possível observar também que, para os três parâmetros avaliados, a utilização de tempo de extração de 10 minutos não apresentou valores significativamente diferentes do tempo de extração de 5 minutos (p > 0,05) para todas as formas de extração utilizadas.…”

“…Estudos prévios sobre o preparo do chá verde têm demonstrado que o modo de preparo, tempo de infusão, forma de acondicionamento da erva, temperatura e a proporção peso seco da erva/quantidade de água utilizada têm grande influência na quantidade de compostos fenólicos e nas atividades antioxidantes extraídas (ASTILL et al, 2001;CHEN et al, 2001;ZHU et al, 1997). No presente estudo, foi avaliado também o efeito do volume de extração, mantendo-se sempre a mesma proporção de erva:água.…”

Identification, quantitation, and method validation for flavan‐3‐ols in fermented ready‐to‐drink teas from the Italian market using HPLC‐UV/DAD and LC‐MS/MS

“…Although the catechin contents in fermented teas are highly variable, the RTD]8 samples profile is comparable, in terms of both qualitative and quantitative profile to those of a real infusion. This variability is confirmed by the dispersion of reference quantitative data, here visualized as error bars corresponding to the reported RSD% [32] and depends, among others, on variety, geographical origin, seasonal changes and harvesting year, climate, preparation, aging, and particle size of tea leaves [32,33]. However, the other teas analyzed showed poor marker profiles most probably due to the preparation process based on a reconstitution of the tea extracts as indicated in the product label.…”