Table 1

Amounts of green tea polyphenols extracted from 2 g green tea leaves by four successive boiling periods of 10 min in 200 ml of water and percentage extracted by chewing green tea leaves

The catechin extraction efficiency of chewing green tea leaves was compared with that of boiling an equal amount of tea leaves in water. Green tea leaves (2 g) were boiled four times for 10 min each in 200 ml of water. An aliquot of this extract was then diluted and analyzed by high-performance liquid chromatography (HPLC). In another experiment, green tea leaves (2 g) were gently chewed for 20 min. The leaves were voided (5–10 ml of saliva), and the subjects washed the mouth vigorously 10 times with water (total volume = 350 ml) in a 2-min period. The leaves and washout were combined and centrifuged. The clear supernatant was then diluted and analyzed by HPLC.

CompoundHot water extractable (mg)Saliva washout (mg/ml)Total saliva amount (mg)% saliva extractable
1st2nd3rd4thTotal
EGCG9.69.17.58.234.54.533.898.1
ECG3.53.12.83.312.71.612.195.1
EGC17.07.74.64.233.42.418.254.6
Epicatechin5.13.12.41.812.41.612.298.3
gAa0.750.610.410.211.981.07.4373
gBa4.42.72.00.8910.00.241.817.7
gCa000000.060.4n/a
  • a These amounts are based on the assumption of similar electrochemical behavior between the unknown compounds and the catechins. The amounts were determined by comparing the peak height of the unknowns to the peak heights of a standard catechin mixture.