The value of drinking tea is achieved through the dissolution of water. Tea polyphenols, caffeine, amino acids and other ingredients constitute the basis of the special flavor of the tea. The composition of tea liquid will be affected by water quality, water temperature, infusion time, tea ratio and other factors.
If brewing green tea with different water quality, the water quality at high pH value and high ion concentration will cause the total individual catechins content decreases, which is mainly caused by the decrease of EGC and EGCG content, however, there are no significant differences in the content of both caffeine and total free amino acids in different water quality.
The dissolution rate of caffeine (mainly affected by the brewing temperature) increases as the brewing temperature rises. The content of caffeine in brewed tea with boiling water is at least double that of the brewing tea at 80 ° C. The content of caffeine in cold brewed tea for 4 hours is only 32.09% of that in boiling water brewed tea for 5 minutes. Total free amino acids are less affected by the water temperature with a very good dissolution rate in both cold brew and hot brew but related to the infusion time.
Catechins change during the brewing process, which can be divided into two categories, the first one depending on the time (EGC and EC) and the second one on the time and temperature (EGCG, GCG, ECG). Due to the long infusion time in the cold brew, the content of EGC and EC in tea liquor is relatively high, while EGCG and ECG are more easily dissolved in high-temperature brewing, the content of these two are relatively low in cold brewed tea.
Inorganic elements in tea liquor mainly are potassium ions with the highest concentration, followed by the order of phosphorus, magnesium, calcium, and sodium. The trend in both cold brew and hot brew teas is the same.
Tea consumers are suggested to adjust the conditions of water quality, water temperature and the way of brewing tea to satisfy personal demand either on the health issue or taste preference.
Translated and edited by Adm./Fong Mong Tea Corp, all rights reserved.