Green tea, oolong tea, White Tea, and Yellow Tea can all be cold brewed. However, not all types of tea are suitable for cold brewing. Generally speaking, the longer the fermentation time of the tea, the richer and more pronounced its aroma and flavor will be. Therefore, for cold-brewing, non-fermented green tea is recommended, as well as oolong tea and white tea with a lower fermentation index.
What Kinds of Tea Can Be Cold Brewed?
The habit of brewing tea with hot water is common among Chinese tea drinkers, but in recent years, “cold-brewed tea” has become a popular new way to enjoy tea. Cold-brewed tea first became popular in Japan, South Korea, and Taiwan due to its convenience, unique aroma, and taste, making it especially favored by younger generations.
Dr. Lin Zhi, Director of Science and Technology at the Tea Research Institute of the Chinese Academy of Agricultural Sciences, explains that brewing tea with hot water is primarily to help the tea's aroma and beneficial compounds dissolve and volatilize more quickly. The chemical substances in tea have different molecular weights and structures, which affect their solubility and dissolution rates in hot and cold water. For example, most amino acids and monosaccharides can dissolve in cold water, whereas caffeine and flavonoids do not dissolve easily in cold water. When tea is cold-brewed, the amino acids that contribute to a fresh and pleasant taste are the first to dissolve, while the caffeine and polyphenols that impart bitterness and astringency dissolve more slowly. This results in a milder, sweeter taste without bitterness or astringency. With extended Steeping times, the tea's aroma gradually becomes more intense, potentially reaching the same concentration as when brewed with hot water. One advantage of cold-brewing is that it prevents the rapid release of too much caffeine and polyphenols, which could irritate the stomach and cause a bitter taste. Another advantage is that it avoids the color changes and vitamin C degradation that can occur under high temperatures. Studies show that cold-brewed tea is not inferior to hot-brewed tea in terms of quality components and sensory experience. Furthermore, there is a polysaccharide in tea that has blood Sugar-lowering properties, which can be better preserved through cold-brewing, making it particularly suitable for those with diabetes.
Not all types of tea are suitable for cold-brewing, according to Dr. Lin Zhi. Generally, premium green teas, lightly fermented oolongs, and white teas like Bai Hao Yin Zhen are good choices for cold brewing. In contrast, highly fermented black teas and Pu'er teas are not recommended. In daily life, green teas and lightly fermented oolongs, when cold-brewed, offer a refreshing and sweet taste and an attractive green color. The best choice for cold-brewing is fresh tea from the current year (mainly to avoid microbial contamination). The water used can be cold tap water, mineral water, or purified water, with mineral water being the preferred option for its natural aroma. Using 500 ml of mineral water as an example, 3 to 5 grams of tea can be added. The duration of cold brewing is also important: high-quality green tea should be steeped for no more than four hours, while lightly fermented teas like Tie Guan Yin and Bai Hao Yin Zhen are best after six hours. It is worth noting that cold-brewed tea should not be left for too long; cold-brews over eight hours old should be avoided to prevent microbial growth.
Cold-brewed tea involves brewing tea with cold water, a method that challenges traditional tea brewing practices. Office workers, students, drivers, hikers, and others can enjoy cold-brewed tea anytime, anywhere, as long as they have access to bottled water.
Traditionally, tea is brewed with hot water, allowing one to savor the elegant aroma and the sweet, smooth flavor of the tea. As people's lives become busier, the lifestyle of drinking cold-brewed tea is becoming increasingly accepted by the public.