Can cold brewed tea and hot tea taste the same when cooled?

When Chinese people entertain guests, they often say "boil water to make tea". Traditionally, tea is always brewed with boiling water. Even high-quality green tea, which is usually brewed at a lower temperature, is generally around 80 °C.

The "cold brewed tea" that has become popular in recent years is brewed at a much lower temperature than the "standard brewing method", and there is even "ice brewing" at refrigerator temperature.

The importance of water temperature for brewing tea

The process of making tea is to extract the soluble substances in the tea leaves with water.

The leaching speed of different substances in tea is affected differently by temperature.

In tea, the dissolutions that have the greatest impact on the taste of tea are caffeine and tea polyphenols, both of which have a bitter taste. The dissolution of caffeine is greatly affected by temperature. It dissolves very quickly at high temperatures, but very slowly below 60°C. The dissolution rate of tea polyphenols is less affected by temperature, and still has a relatively good dissolution rate at lower temperatures.

Another ingredient that has a great influence on the flavor of tea (especially green tea) is theanine, which has a sweet taste. The dissolution rate of theanine is less affected by temperature and dissolves quickly at low temperatures.

Green tea and water temperature

In green tea, tea polyphenols mainly exist in the form of catechins, and it also contains relatively large amounts of theanine.

If the water temperature is high, caffeine will dissolve quickly into the water, making it bitter; if the water temperature is lowered, tea polyphenols and caffeine will decrease, while theanine will hardly decrease. With the decrease of tea polyphenols and caffeine, the bitter taste will not be so strong, and the relative amount of theanine will increase, so the refreshing taste it brings will be more prominent, and the ability to cover up the bitterness will be stronger.

Considering the dissolution rate and total amount of various flavor substances, it is recommended to brew general green tea with hot water at 70°C to 85°C. By controlling the tea-to-water ratio and time, you can get better-tasting tea.

Traditional method of brewing black tea

In black tea, tea polyphenols mainly exist in the form of theaflavins, which can combine with caffeine to form a relatively stable complex, making them less efficient in producing a "bitter" taste.

Black tea also forms many aromatic substances during the processing, and high-temperature water is conducive to their release. Therefore, most black teas are generally recommended to be brewed with boiling water.

Other types of tea have their own characteristics in details, but in general, they are similar. In short, they all use relatively high temperature water to extract the soluble substances in the tea leaves in a relatively short time, forming a rich and strong flavor and taste.

What’s so special about cold brew?

However, many people still find the tea obtained by the "standard brewing method" to be more bitter, and drinking hot tea in summer is not so comfortable. Therefore, "cold brewing tea" came into being.

Cold brewing is a method of soaking tea leaves in water at room temperature. It uses a longer soaking time to compensate for the problem of slowing down the leaching speed caused by low temperature. At low temperatures, although the leaching speed is slow, as long as the time is long enough, enough ingredients in the tea leaves will be dissolved.

Because the dissolution rate of different substances is affected by temperature to different degrees, the composition of flavor substances obtained after extending the soaking time is different, and the flavor obtained is different from that of "hot brewed tea" after cooling down. Specifically, caffeine dissolves very little, while tea polyphenols will still dissolve in large quantities after sufficient time. If there is theanine, it can also be fully dissolved. Therefore, in cold-brewed tea, the relative content of caffeine is greatly reduced, while the relative content of tea polyphenols and theanine is increased. The resulting tea has basically no bitterness, but the tea aroma is still obvious and the taste is relatively sweet.

Some people are concerned about whether the "nutritional value" of cold-brewed tea is better or worse than "hot-brewed tea", which is an unnecessary entanglement. The "nutritional ingredients" in tea are very few and can be completely ignored, while the "core ingredients" in tea, such as caffeine, tea polyphenols, and theanine, mainly affect the flavor of tea. The health value is "good to have, but not important", and it is not worth considering their amount for health reasons.

What kind of tea is suitable for cold brewing?

From the previous explanation, we can see that no matter whether it is hot brewing, cold brewing or ice brewing, the goal is to make the tea taste good, and the core is the dissolution of soluble substances in the tea leaves. In theory, any kind of tea can be cold brewed, the only difference is whether it tastes good or not, and whether it tastes good or not is actually a very subjective thing...

From my personal experience, tea leaves with delicate leaves and full rolling are easier to dissolve, and cold brewing is easier to bring out the flavor. For example, green tea, black tea, white tea, scented tea, etc., will taste good when cold brewed, while rock tea and Pu'er raw tea are not easy to taste good when cold brewed.

What should you pay attention to when brewing cold tea?

Cold brewing takes a long time, and many people worry that it may go bad.

Except for Pu'er tea and other dark teas, the water content of other teas is very low. Under normal storage conditions, bacteria will not grow, so there are very few bacteria on tea leaves. Drinking water, which is usually used to make tea, also has very few bacteria. If you put tea leaves in water and soak them at room temperature, an hour or even less is enough to brew them into a good taste. During this time (or longer, up to two or three hours), bacteria will not grow to a harmful level.

If you put it in the refrigerator for "cold brewing", the temperature is low, the substances in the tea dissolve more slowly, and it takes longer to brew a strong flavor. In this case, it is the same as putting prepared food in the refrigerator for refrigeration. If the amount of tea is large (for example, a tea bag in 500 ml of pure water), it may take more than 4 hours to have a strong flavor - in the refrigerator, it can be brewed "overnight" or even for a day or two, and it will not go bad.

In addition, at lower temperatures, the substances in the tea leaves will dissolve to a certain extent and it will be difficult to dissolve them again. Therefore, after cold brewing once, it is generally difficult to obtain a strong flavor if the remaining tea leaves are cold brewed again. Such residues can also be brewed with hot water, and it should be possible to obtain tea with a good taste.

Author: Yun Wuxin

Editor: Li Xiaokui