The polyphenols content was determined by ferrous tartrate
colorimetry [17]. In general, the tea extract (0.5 g) was dissolved in 50 mL boiling water and kept in water bath at
100 ◦
C for 30 min. Two millilitres were put into 8 mL distilled water after cooling, 10 mL of 3.6 mM ferrous tartrate
and 30 mL of 200 mM phosphoric acid buffer solution were
added. The absorption values of mixed solution were measured at a wavelength of 540 nm using spectrophotometer.
The tea polyphenol content was calculated according to the
formula, Where A is the absorbance value of the solution