Why do some teas taste fresh, sweet, and refreshing while others do not? Why do some people say tea leaves have a seaweed flavor, while others describe the tea soup as resembling thick chicken broth? Why do some teas appear snow-white all over, while others always have a layer floating on the surface of the tea soup when brewed... What is going on with all these phenomena? It can be confirmed that these are all related to the amino acids in tea. This article attempts to help everyone simply understand the amino acids in tea.

1. What exactly are amino acids?

We all know more or less about "amino acids." Since childhood, many of the supplements our parents bought prominently featured "amino acids" on the label. I remember that canned milk powder often drunk during school days also listed the content of protein and amino acids on the back ingredient list. So, we generally have some memory—amino acids are something good and beneficial for the human body. Today, as we pursue pure natural goodness, where do we find such pure natural amino acids? For food, there are seaweed, meat, beans, mushrooms, etc., and for drinks, tea is actually a solid and good choice.

Tea contains about 1% to 4% amino acids, with 26 types discovered, including 20 protein amino acids and 6 non-protein amino acids. Among them, the main ones are theanine, glutamic acid, aspartic acid, and arginine. Especially theanine, which is almost unique to tea, accounts for 1% to 2% of the dry matter of tea and about 50% of all amino acid content. Therefore, when we discuss tea amino acids, we mainly study theanine.

Composition of tea tree amino acids:

In tea leaves, amino acids are a very important class of metabolites in the nitrogen cycle. That is, nitrogen nutrients are absorbed by the roots and then transported to various parts of the tea tree such as buds and leaves, allowing the tea tree to grow slowly and accumulate more and more natural amino acids, which are discovered and utilized by humans. Tea amino acids not only represent the supply and transformation of tea tree nutrition but also have a direct and important relationship with the quality of tea, almost to an indispensable degree.

2. What is the relationship with tea quality?

Answering the questions raised at the beginning, most tea amino acids have the characteristics of being fresh, refreshing, and sweet, with some amino acids also slightly sour. If the amino acid content in tea is relatively high, then the taste will be fresh, refreshing, and sweet. If the content of the stimulating tea polyphenols is also appropriate, then the tea's taste will show a mellow and refreshing characteristic.

In essence, amino acids are one of the three most important categories of substances that make up tea taste (tea polyphenols, amino acids, caffeine). Whether the tea soup tastes good or not largely depends on the content and proportional relationship of these three types of substances.

Some amino acids also exhibit certain pleasant aromas, such as腥甜 (fishy-sweet), seaweed flavor, fresh sweetness, laver scent, etc. These sensations are often found in Japanese steamed green tea or some famous and high-quality tender green teas. This is because these teas generally have high amino acid content. In addition, some amino acids can combine with other substances and participate in the formation of good aromas during the tea-making process.

Therefore, the relationship between tea amino acids and tea quality can be simply summarized as one of the three kingdoms of taste and the优劣 (good and bad) of aroma.

3. Which teas contain more amino acids?

Alright, we know tea amino acids are good. So when buying tea, which type of tea tends to have higher amino acid content? Here's a simple trick: the more fine hairs (hao) the tea has, the higher the amino acid content often is.

Sometimes when we brew tea, a layer of white fine hairs floats on the surface of the soup. Many friends think the tea soup is not clean, mistaking it for dust, but that's not the case. These are the natural fine hairs growing on the tea leaves themselves. The younger parts contain more tea hairs, and the main components of tea hairs include amino acids. Therefore, whether it's白毫 (white hair) or金毫 (golden hair), it's best to observe carefully when tasting tea to distinguish whether it's真正的浑浊 (real turbidity) or "假浑浊 (false turbidity)."

4. What are the distribution patterns of amino acids?

Beyond simple tricks, tea amino acids exhibit more distribution patterns under different tea tree varieties, planting environments, cultivation measures, and processing techniques. This is determined by the synthesis principles and biochemical-physical characteristics of tea amino acids. Understanding these gives us a clearer concept of grasping tea quality.

(1) For different tea tree varieties: Small-leaf varieties contain more amino acids than large-leaf varieties, and the tender parts of small-leaf varieties contain more than the coarse old parts. Therefore, we seem to always pursue tender tea, always feeling that the younger the tea leaves, the better the quality, which actually makes sense.

(2) For different planting environments: Tea grown in the north has higher latitude, relatively low temperature, relatively weak sunlight, and contains more amino acids, while tea grown in the south has lower latitude, relatively high temperature, relatively strong sunlight, and contains relatively fewer amino acids. At the same latitude, high-altitude mountain tea contains more amino acids than low-altitude hill tea. The common saying "high mountains and clouds produce good tea" is very much related to this.

(3) Tea trees grown using shading methods have relatively higher amino acid content, such as Japanese煎茶 (sencha). Some tea gardens plant shade trees precisely to block part of the sunlight, thereby causing the tea leaves to produce more amino acids.

(4) Among the six major tea categories made with different tea-making processes, non-fermented famous and high-quality green teas and well-controlled post-fermented black teas contain more amino acids. The former process can maximally preserve the original amino acids in the fresh leaves, while the latter process can synthesize a large number of amino acids during post-fermentation (mainly through microbial action).

5. What are the effects of amino acids?

In human physiological processes, amino acids are the basic units for synthesizing peptides and proteins. Usually, two amino acids lose one molecule of water to become a dipeptide, and n amino acids lose n-1 molecules of water to become polypeptides or large-molecule proteins. Tea amino acids provide the amino acids necessary for human physiological metabolism, thereby promoting the normal functioning of human physiological functions.

Relevant experiments have proven that tea amino acids help the brain enter a state, having a good auxiliary effect on human mental activities such as thinking, memory, and learning.

Tea amino acids can also inhibit the excitement caused by caffeine in the human body, calming people down and promoting concentration.