What teas are suitable for cold brewing?

In the scorching summer, a cup of cold brewed tea is refreshing and sweet, taking away the feeling of stuffiness. So what kind of tea is suitable for cold brewing? To understand this problem, it is necessary to first understand the principle of low-temperature extraction of tea leaves in order to easily brew good tea!

How does low-temperature extraction affect the quality of tea soup

The process of brewing tea is essentially the migration of soluble substances from tea leaves to water. Traditional hot soaking can quickly dissolve various components within a few minutes, including amino acids and sugars that bring fresh sweetness, as well as caffeine and tea polyphenols that bring bitterness. Cold foam, on the other hand, utilizes a low-temperature environment to selectively affect the dissolution of different components.

Cold brewed tea is usually extracted at 4-20 ℃ for several hours. Through this extraction method, it can effectively avoid damaging or evaporating the aroma components and sensitive flavor substances in the tea leaves. The aroma, taste, and color components in the tea gradually dissolve into the water, forming a unique flavor tea soup. Therefore, cold brewed tea usually has a softer taste, lower bitterness, and a fresher aroma.

1. Fresh and sweet substances (amino acids, soluble sugars) dissolve quickly

Under low temperature conditions, the thermal motion rate of molecules is significantly reduced, which allows amino acids with small molecular weight and strong polarity (such as theanine), soluble sugars (such as sugar and glucose), and other fresh and sweet substances in tea to dissolve preferentially due to their high diffusion coefficient.

2. The dissolution of bitter substances (caffeine, ester catechins) is inhibited

Under low temperature conditions, the dissolution kinetics of ester catechins (such as EGCG) and some caffeine with high molecular weight and hydrophobicity in tea are significantly inhibited.

Research has found that at temperatures around 5 ℃, amino acids with small molecular weight and strong polarity, as well as non ester catechins, are more easily dissolved, while ester catechins such as EGCG are more difficult to dissolve. Therefore, the taste of tea soup is fresh, sweet, and without obvious bitterness, creating a natural low phenol ammonia ratio tea soup.

3. Low temperature allows the aroma of cold brewed tea to dissolve into the tea soup

For aroma, due to the low temperature environment simultaneously inhibiting the activity of hydrolytic and oxidative enzymes, a large amount of aroma precursor substances in the form of glycosides (such as linalool glycosides and geraniol glycosides) are retained in the tea soup. Although they do not directly present a fragrance before consumption, these precursor substances can be slowly released during subsequent storage or oral enzymatic hydrolysis, resulting in a long-lasting and layered aroma.

4. Low temperature preserves the color of the tea soup

In addition, cold brewed tea has significant advantages in preserving the color of the tea soup. It can effectively retain chlorophyll in tea leaves, keeping the tea soup fresh green and bright in color, while promoting the dissolution of yellow flavonoids, avoiding yellowing of tea soup caused by high temperature. In addition, cold soaking can significantly enhance the brightness of tea soup, making it clearer and more transparent, resulting in better sensory quality.

Which teas are suitable for cold brewing?

Most types of tea can be brewed cold. Generally, 500g of tea is brewed with 500mL of 4 ℃ cold water and left to stand for 4 hours. If brewed with room temperature water, it only needs to be left to stand for 2 hours. Generally speaking, green tea and white tea with high amino acid content, as well as high aroma oolong tea and black tea, are suitable for cold brewing.

Green tea: High in amino acids, fresh and sweet substances are preferentially dissolved at low temperatures, while ester catechins with a bitter taste are less dissolved. When brewed cold, it is fresh, refreshing, and sweet, with extremely low bitterness.

White tea: It is rich in amino acids, and under low-temperature extraction, its fragrance and sweetness are particularly prominent, with a clear and sweet taste.

Oolong tea: Low temperature can effectively preserve its aroma precursor substances, resulting in a clear and elegant floral aroma and a soft taste in the tea soup.

Black tea: Low temperature extraction can effectively present the sweetness of black tea while avoiding the possible sourness caused by high temperatures.

Pu erh ripe tea, black tea, and heavily roasted rock tea: Due to their high degree of fermentation or heavy roasting, their flavor substances are not efficiently dissolved at low temperatures, resulting in a weak taste and aroma in the brewed tea. Cold brewing is not recommended.

Precautions

Container: It is recommended to use wide mouthed glass bottles for easy tea infusion and residue filtration.

Storage: Tea soup extracted at room temperature is recommended to be consumed within 8 hours; Refrigeration can store for about 24 hours. After this period, avoid drinking to prevent microbial growth.

In short, by controlling the soaking time and conditions reasonably and selecting the right tea, one can obtain a cold brewed tea with online appearance, balanced flavor, and comfortable taste.