Why do we rinse tea leaf?

We often rinse tea leaves before brewing. Do you really know the reason for it? Some people say it is because Chinese tea is often contaminated by pesticide and rinsing is a cleansing process to remove it. Of course, this is not true. If pesticide is used, it is applied in late spring or summer when the weather becomes warmer and pests become an issue. Farmers will not apply pesticide on freshly germinated leaves in spring. The pesticide applied in late spring or summer is absorbed by the tea plant through its roots and stays inside the cells. Technically, there is no way to remove pesticide by rinsing even if it is used. So what actually is the reason to rinse tea?

3 reasons for rinsing tea leaves

From my point of view, there are three reasons why we rinse tea.

1. To unfurl the tea leaves
2. Maintain high brewing temperature
3. For short-time brewing

1. Open tea leaves

Some oolong teas, such as Taiwan oolong and Anxi oolong like Tie Guan Yin, are tightly rolled into ball shape. Pu-erh tea is often compressed very hard into disc or brick shape. If we brew these teas without rinsing, water may not penetrate inside and only moisten the surface. This will result in very inconsistent brewing. With rinsing once or twice, these teas will loosen and unroll. Usually, the better the quality, the faster the unrolling speed. We need to adjust the rinsing time according to the quality of the tea.

2. Maintain high brewing temperature

The flavor and taste of fermented tea such as oolong and black tea are composed of substances like terpenes and conjugated polyphenols. These substances are produced as a result of enzymatic fermentation. These substances have less affinity than polyphenols found in non-fermented tea like green tea. Hence, it is important to use higher temperature to efficiently extract these substances when brewing fermented tea. Many people think that boiling water is at 100°C. However, if we measure the actual temperature of hot water right after heating stops, it is about 95°C. Once it is poured into a teapot, the temperature drops about 10°C in summer and nearly 20°C in winter. In addition, dry tea leaves also contribute to cooling the water by another 10°C. If no rinsing is carried out, you are actually brewing tea at 65–75°C. This is not hot enough to bring out the flavor and taste of fermented tea. Therefore, it is very important to warm up the teapot with boiling water for 10 seconds, and then rinse the tea leaves with boiling water for a few seconds. It is not very common to rinse black tea, but some people do so when practicing the Gong Fu brewing technique.

3. For short-time brewing

Naturally farmed tea contains a lot of polyphenols or their oxides. As mentioned above, the main taste components of fermented tea are also polyphenol oxides. To brew these teas well, the key is how to extract these substances. Since they have less affinity with water, it is important to use water at higher temperature. However, tea may be damaged if the water temperature is too high. To minimize damage, we should practice the “high temperature and short time” brewing technique. It is said that this method causes less damage compared to lower temperature and longer brewing time. To achieve this, some preparation is needed. First, warm up the teapot with boiling water for about 10 seconds. After adding the tea leaves, rinse them once or twice quickly. The leaves will then unroll and become easier to extract. Usually, after rinsing, I put the lid back on and leave the leaves for about 10 seconds. The hot steam remains inside the teapot, which further prepares the leaves for brewing. With this method, we can extract sufficient flavor even if the brewing time is only a few seconds. The same technique can be applied to green or black tea, but rinsing must be done very quickly.