Chinese tea, the magical leaves of the East, has a long history and contains thousands of things. There are endless codes in it, waiting for us to decode. To discover tea and interpret the code of tea, first of all, start with the chemical composition of tea. The taste of tea is a comprehensive reflection of the changes in dozens of flavors. Different tea leaves have different tastes due to their different types, contents, and ratios of flavor components. The content of tea is very rich. So far, there are more than 700 known compounds in tea that have been isolated and identified.
1. Moisture (75%～78%)
Moisture is an essential ingredient in the life activities of tea trees, and an important medium for a series of chemical changes in the tea making process. The change in the color and aroma of tea leaves during the tea making process is accompanied by changes in moisture. Therefore, the change of water content is often used as an important biochemical index to control quality when making tea.
The water content of fresh tea leaves is generally 75% to 78%, and the fresh leaves are old and tender, tea tree varieties, seasons, and water content are also different. Generally, young bud leaves, rain leaves, dew leaves, and large-leaf species have higher water content in the rainy season and spring, while the old leaves, medium and small leaf species, and dry season and sunny leaves have lower water content.
2. Tea polyphenols (accounting for 20% to 35% of the total dry matter)
Tea polyphenols are the general name of more than 30 polyphenols compounds with catechins as the main body in tea plants, also known as "tea tannins" and "tea tannins", including catechins, flavonoids and Flavonoid glycosides, anthocyanins and anthocyanins, phenolic acids and depsid acids are four major types of substances.
Tea polyphenols are a very important compound that distinguishes tea from other plants, and it is the primary component of tea's health function. The content of tea polyphenols generally accounts for 20% to 35% of the total dry matter. The content of polyphenols in tea is affected by many factors, such as the environment, tea tree varieties, and the degree of aging.
Of the total amount of tea polyphenols, catechins account for about 70%, which are important components that determine the color, aroma and taste of tea.
3. Protein (20%-30% of the total dry matter)
The protein content of tea leaves accounts for 20%-30% of the dry matter mass, and the protein content that can be dissolved in water and used directly accounts for only 1%-2%. This part of water-soluble protein is one of the ingredients that form the taste of tea soup.
4. Amino acids (accounting for 1% to 4% of the total dry matter)
Amino acids are the basic substances that make up protein, and the content accounts for 1% to 4% of the total dry matter. The amino acids in tea have been found to have 26 kinds of theanine, glutamic acid, aspartic acid, etc., and the seasonal changes of various amino acids are obvious. The total amount of amino acids shows a trend of high in spring, low in autumn, and middle in summer. The reason why spring tea is fresher.
For tea, amino acids are a treasure and the main contributor to the refreshing taste of tea. It not only neutralizes the bitterness and astringency of polyphenols and caffeine in the mouthfeel, but also can evolve a fascinating aroma that is endless. It is an indispensable part of high-grade tea.
5. Alkaloids (accounting for 2%～5% of the total dry matter)
The alkaloids in tea include caffeine, theobromine and bar alkali. Among them, the content of caffeine is the largest, accounting for about 2% to 5% of the total dry matter; the other content is very small.
Caffeine has a bitter taste. The content of caffeine varies greatly in various parts of the tea plant. The leaves are the most, and the stems are less. In the new shoots, it decreases with the aging of the leaves and changes significantly with the season. Generally, summer tea Spring tea is high in content.
Caffeine is easily soluble in water and is an important substance that forms the taste of tea. It can also be used as one of the characteristics of authentic tea. Caffeine has a variety of pharmacological effects on the human body, such as refreshing, diuretic, promoting blood circulation, and assisting digestion.
6. Sugars (20%-25% of the total dry matter)
The sugars in tea include monosaccharides, oligosaccharides, polysaccharides and a small amount of other sugars. Its content accounts for 20% to 25% of the total dry matter.
Monosaccharides and disaccharides, also known as soluble sugars, are easily soluble in water, with a content of 0.8% to 4%. They are one of the substances that make up the flavor of tea. The polysaccharides in tea include starch, cellulose, hemicellulose, and lignin, and the content accounts for more than 20% of the total dry matter of tea. Polysaccharides are insoluble in water and are an important component to measure the ageing and tenderness of tea. Tea has low tenderness and high polysaccharide content; high tenderness and low polysaccharide content.
7. Pectin (accounting for 4% of the total dry matter)
Pectin and other substances in tea are sugar metabolites, and the content accounts for about 4% of the total dry matter. The presence of pectin is conducive to manual kneading and forming during tea processing, and is related to the viscosity of the tea soup. Water-soluble pectin is one of the main components that form the thickness and gloss of the tea soup.
In addition, there are many beneficial ingredients.