Green tea can be cold brewed, a method that offers a different flavor profile compared to traditional hot steeping. The process, known in Japan as mizudashi, relies on a slow, gentle extraction that changes which compounds are released from the tea leaves. This technique yields a beverage that is smoother, sweeter, and less astringent than its hot-brewed counterpart.
The Cold Brew Method
The process for cold brewing green tea is straightforward. Select a clean, sealable glass pitcher or jar, preferably glass to avoid retaining odors or flavors. The recommended ratio is approximately 15 grams of loose-leaf green tea for every one liter of water, or one tablespoon per 8 to 10 ounces of water.
Use cold, filtered water, as water quality impacts the final flavor. Combine the loose leaves and water in the container, ensuring the leaves are fully submerged. Seal the container and place it in the refrigerator.
The steeping time is variable, generally ranging between 6 and 12 hours, or overnight. Some Japanese green teas may require as little as 15 minutes. Taste testing after six hours determines the ideal strength.
Once the desired flavor is achieved, the tea must be strained immediately to halt the brewing process. Pour the liquid through a fine-mesh strainer or cheesecloth into a separate serving vessel, discarding the spent leaves.
Flavor and Chemical Differences
The difference in taste between hot and cold-brewed green tea results from how temperature affects the solubility of chemical compounds. Hot water rapidly extracts compounds that contribute to bitterness and astringency. Cold water, conversely, is a slower and more selective solvent.
Cold water extracts fewer tannins and catechins, such as epigallocatechin gallate (EGCG), which cause astringency. Since these bitter compounds are less soluble at low temperatures, the resulting cold brew is smooth and lacks harshness. This gentler extraction allows the tea’s natural sweetness to emerge.
The amino acid L-theanine, responsible for the savory umami flavor and sweetness, is highly soluble even in cold water. Cold brewing preserves this compound, making its presence more pronounced since it is not masked by bitter catechins.
Cold brewing also results in a lower concentration of caffeine compared to a standard hot brew. Since caffeine extraction is temperature-dependent, studies suggest cold-brewed tea can contain one-third to one-half less caffeine than the same tea prepared hot.
Selecting the Right Green Tea
The quality of the leaf is important when choosing green tea for cold brewing, as the slow process highlights the tea’s inherent characteristics. High-quality, loose-leaf green teas are recommended over tea bags, which often contain broken fragments that can lead to a cloudy brew.
Japanese green teas are particularly well-suited for cold brewing due to their unique processing methods. Varieties like Sencha and Gyokuro are excellent choices. Sencha offers a refreshing, grassy flavor, while shade-grown Gyokuro provides a deeper, more intense umami and sweetness.
The strained tea should be kept refrigerated in a sealed container to prevent absorbing other odors. For the best taste and quality, the cold brew should be consumed within three to five days of preparation.