In the world of tea, the debate between cold brew tea and hot brew tea is heating up. Many people wonder if these two brewing methods can produce similar flavors. In Chinese culture, it’s common to say “boil water to brew tea,” as traditionally, tea is steeped with boiling water. Even high-quality green teas typically use water around 80°C (176°F). Recently, the trend of cold brew tea has gained popularity, with some methods even using refrigerator temperatures.

The Science of Brewing Temperatures

Brewing tea is all about extracting soluble compounds from tea leaves using water. The extraction speed varies with temperature, significantly affecting flavor. The main components influencing tea taste are caffeine and tea polyphenols, which can impart bitterness. Caffeine dissolves quickly at high temperatures but is slower to extract below 60°C (140°F). In contrast, tea polyphenols still extract well at lower temperatures, while L-theanine, known for its sweet flavor, is less affected by temperature.

Green Tea and Brewing Temperature

For green tea, tea polyphenols exist mainly as catechins, along with L-theanine. If brewed with hot water, caffeine extracts quickly, leading to bitterness. Lowering the temperature reduces caffeine and tea polyphenol extraction while preserving L-theanine. This results in a less bitter tea with a sweeter flavor profile.

For the best taste, brew green tea with water heated to 70°C to 85°C (158°F to 185°F). By managing the water-to-tea ratio and steeping time, you can create a delicious cup.

Traditional Brewing for Black Tea

In black tea, tea polyphenols mainly exist as theaflavins, which can reduce bitterness when combined with caffeine. The processing of black tea also develops aromatic compounds that release best with boiling water, making it advisable to steep most black teas with boiling water. Other tea types have their unique characteristics, but the general principle remains: use high temperatures and shorter steeping times for rich, flavorful brews.

What’s Unique About Cold Brew?

Many people find hot-brewed tea overly bitter, especially during hot summer months. This is where cold brew tea shines. Cold brewing uses room temperature water and longer steeping times to enhance flavor extraction. While the extraction process is slower, a longer steep allows for adequate flavor compounds to dissolve.

Due to varying extraction rates, cold brew tea has a different flavor profile than cooled hot tea. Caffeine levels drop, while tea polyphenols and L-theanine still extract effectively, resulting in a sweet and aromatic tea without the bitterness.

Which Teas Are Best for Cold Brewing?

Theoretically, any tea can be cold brewed, but the taste can vary. Personally, delicate, well-rolled teas like green tea, black tea, white tea, and floral teas tend to cold brew well. In contrast, heavier teas like rock tea and raw Pu-erh may not yield satisfying results.

Tips for Cold Brewing Tea

Cold brewing requires a longer steeping time, which raises concerns about spoilage. However, most teas (except for Pu-erh and other dark teas) have low moisture content, reducing the risk of bacterial growth. Under normal conditions, bacteria levels are minimal. When steeping at room temperature, one hour (or even less) is often enough to extract great flavors, and steeping for two to three hours remains safe.

If cold brewing in the fridge, the low temperature slows extraction further, requiring more time for robust flavor. For larger amounts (like one tea bag in 500 ml of water), it might take four hours or longer to achieve a good taste. Cold brewing can last overnight or even a day or two without spoiling.

Finally, once the tea leaves have been cold brewed, they won’t extract well a second time. However, you can still use the same leaves for a hot brew, which should yield decent flavor.