Easy Way to Prepare Flavorful and Warm Tea at the Workplace | HOJO Online Speciality Tea Shop

Have you ever experienced the transformation of tea stored in a thermos or water bottle at work, turning into a brown hue and acquiring a bitter, astringent taste? As this has piqued the interest of many, I would like to offer a more in-depth explanation for a solution.

Tea stored in a thermos undergoes oxidation due to heat

Tea is rich in polyphenols, serving as antioxidants that act as protective shields. These antioxidants undergo oxidation themselves, preventing the oxidation of other substances—hence the term “antioxidants.” Because of this inherent quality, the antioxidants in tea are highly prone to oxidation. When warm tea is stored in a water bottle or thermos, oxidation occurs, resulting in green tea adopting a color akin to black tea, accompanied by an intensified astringency.

In particular, catechins, a type of polyphenol in tea, undergo oxidation and conjugate with each other, resulting in the formation of tannins. These tannins are responsible for the brownish color and astringency. Once tannins are formed, the process cannot be reversed. Freshly brewed green tea undergoes a transformation into a brownish tea, resembling an incomplete version of black tea.

Moreover, oxidation goes beyond polyphenols; chlorophyll, a green pigment present in tea leaves, also undergoes oxidation. Chlorophyll contains magnesium at its molecular center, and during oxidation, the bonds holding magnesium break, leading to its liberation. The released magnesium significantly contributes to the astringency and bitterness. For further details, please refer to the following column.

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How to easily enjoy delicious tea at the workplace?

Storing hot tea for an extended period can lead to oxidation and a change in color to brown. However, if you refrigerate the tea, it remains fresh with minimal oxidation. To achieve this, brew a highly concentrated tea, chill it, and bring it to work in a thermos. You can then mix this concentrated tea with hot water.

The key points to consider are as follows:

1. Use a minimal amount of hot water, aiming for around 200ml for 5g of tea leaves.
2. Allow the tea to steep for nearly 30 minutes to extract the maximum flavor intensity.
3. Cool the brewed tea rapidly and thoroughly.

Detailed brewing instructions

There are various types of tea, such as Japanese tea, black tea, and oolong tea, but you can generally follow the same method.

First, preheat a teapot and add 5g of tea leaves with 100-200ml of hot water. Cover it and let it steep for about 30 minutes. For the concentrated tea base, make it as strong as possible. When drinking tea at work, dilute the base tea with hot water, aiming for about a 5 times dilution. For example, if you want to drink 100ml of warm tea, use 20ml of the base. By preparing 200ml of the base, you can enjoy the equivalent of at least 1 liter of tea.

This method may seem unconventional with a 30-minute steeping time, but it surprisingly results in flavourful tea. Moreover, when diluted five times with hot water, the tea remains as hot as freshly brewed tea. Mastering this technique allows you to effortlessly enjoy delicious tea during your workday.

When bringing tea to the workplace, there’s no need to brew it on the same day. You can prepare the tea a day in advance, refrigerate it, and it will remain fresh for about three days. The crucial factor is to rapidly cool down the concentrated tea, minimizing the oxidation of the hot base tea. This ensures that the tea maintains its freshness and flavor, allowing you to enjoy a delightful cup even when prepared in advance.