Abstract
This study is to determinate the percentage of caffeine and tannin in green tea by three Libyan traditional methods and the effect of heating time. Also, it aimed to study the nutritional healthy benefits and side effects of these constituents. Three samples of vert chine chunmee (NAPT) of green teas were analyzed. The first sample was raw, the second sample was boiled for 30 minutes and the third sample was boiled for 5 minutes. The heating temperature was at 100C. The percentage of tannin and caffeine were estimated in each sample. Caffeine percentage in the three samples was 0.021, 0.022, 0.012, respectively. Tannin participation in green tea prepared by second Libyan traditional method (green tea boiled for 30 minutes) has 83mg/100ml of tannin. This value is higher than raw and third Libyan traditional method (green tea boiled for 5 minutes), which it was 10.9 mg/100 ml and 49mg/100ml, respectively. This study reveals that the heating time affects on the percentage of caffeine and tannin in green tea; as the heating time increases, the percentage of caffeine and tannin increases. But the percentage of tannin in green tea prepared by traditional Libyan methods was higher than caffeine. The rise in tannin percentage in green tea may lead to genetic defect; therefore, the third Libyan traditional method (boiling time for 5 min) may nutritionally consider the best for improving human health, followed by the first Libyan method. They