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Effect of multiple extractions and water-ethanol ratio on the bioactive composition and antioxidant capacity of Yinzhen tea

Tea is one of the most widely consumed beverages in the world. Its health benefits attributed to antioxidant, anticarcinogenic, and antiallergic activities are the results of a rich polyphenolic content and composition. This study examined the effect of extraction solvents (water, 10%, 25%, 50%, 75% and 100% ethanol) and multiple extractions(1st, 2nd, 3rd) on the composition and antioxidant capacity of Yinzhen tea in loose leaf form. Total polyphenol and flavonoid contents, as well as the antioxidant capacity were measured spectrophotometrically, while individual catechins and methylxanthines were quantified using HPLC-PDA. The highest polyphenol content and antioxidant capacity were determined in 75% ethanol tea extract. The most abundant catechin was EGCG, with the highest content determined in 50% ethanol extract (429.82 mg/L). The application of lower ethanol concentration (50% or less) was the most efficient for extraction of catechins.

extraction solvent; HPLC; polyphenols; methylxanthines; multiple extraction; yellow tea

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