METHOD OF DETERMINING POLYPHENOLS IN TEA Russian patent published in 2014 - IPC G01N33/02 

FIELD: chemistry.

SUBSTANCE: method involves extracting polyphenols from a crushed tea sample; determining concentration of polyphenols in the extract by a colorimetric method using Folin-Ciocalteu reagent, wherein the extract is obtained using a crushed tea sample weighing 1.0-1.5 g and 50-75 cm³ water at 95-100°C; steeping for 5 minutes at room temperature and filtering; diluting the obtained extract with water 25 times, collecting 0.5-0.6 cm³ of the diluted extract; adding 3.0 cm³ of a 0.5 M Na₂CO₃ solution and 0.3 cm³ of Folin-Ciocalteu reagent and measuring optical density of the solution at wavelength 765 nm after 2-3 min; determining concentration of polyphenols in the diluted extract from a calibration curve of optical density of tannin solution versus weigh concentration of tannin in the solution; the amount of polyphenols in tea transferred into the aqueous extract is expressed through its weight fraction in the analysed tea sample X, % per dry substance, which is calculated using a formula.

EFFECT: faster analysis, reducing the number of simple operations and low consumption of reagents.

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