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Biochemical composition of Shan Tuyet tea

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Tea is a beneficial drink and a precious herb because the medicinal substances in tea help the human body to prevent and cure several diseases very effectively. In 2006, WHO announced, “The number 1 drink of choice for health is tea”. Shan Tuyet tea is full of value and has high nutrient content. So what’s so special about tea?

Country:

The water content in tea leaves gradually decreased from bud tea leaves to old tea leaves (bud tea 76.6%; single-leaf tea 75.6%; two-leaf tea 75.6% and three-leaf tea 74.26%). The variation depends on the age, the geographical distribution of the tea tree, cultivation practices, and time of harvest (time of day, month, season).

Solubilizer:

It is a mixture of many different substances, soluble in boiling water and an important quality indicator of raw tea and tea products. In this mixture, about 50% are phenolic compounds; the remaining 50% are soluble fluids, proteins, amino acids, alkaloids (mainly caffeine), pigments, vitamins, and enzymes.

Tanin:

The characteristic of tannin is an acrid taste. It is an essential substance in raw materials, significantly affecting tea quality, taste, aroma and other properties determined by tannin.

The more tannin in the tea, the higher the quality of the tea. However, it depends on the amount of tannin dissolved in Oxydietyl. There are many tannins, but the quality is worse in the combined state.

The amount of tannin in tea more or less depends on age, picking period, tea variety, environmental conditions, and processing method.

The amount of tannin is unevenly distributed on the same tea bud, most concentrated in tea buds (39.9%), then young leaves (first leaf 36.8%; second leaf 36.1%; third leaf 29.25%; old stem 25%). Tannin can combine with Albumin to form an insoluble substance vital for tea processing.

Tannins combine with caffeine to form an insoluble substance that scum on the water’s surface when the tea is cooled.

Protein and Amino Acids: accounted for 22% – 26% of dry matter:

Through processing, the content of protein and amino acids changes: the number of proteins decreases and the amount of amino acids increases. Due to the hydrolysis process, a part of tea protein forms amino acids during processing.

Free amino acids react with the catechin derivatives of tea to form aldehydes with a pleasant aroma to tea.

* Albumin (simple protein): Albumin is a nitrogen-containing organic substance, a major structural component of organisms. Albumin content in tea is extensive and varies depending on many conditions, such as picking periods, young or old leaves, and external conditions.

E. Alkaloids (mainly caffeine):

Caffeine makes up 3-5% of tea by weight. The amount of caffeine in tea is four times more than in coffee (according to Muller).

Caffeine stimulates the human body, first of all stimulating the central nervous system, creating a feeling of euphoria and comfort, improving the working capacity of bones and muscles, and helping with urination.

The amount of caffeine in tea varies depending on external circumstances, preservation techniques, tea varieties, picking time, and geographical location.

Free caffeine exists in fresh tea leaves more than in finished tea. During the manufacturing process, some caffeine combines with other substances to reduce the amount of free caffeine. Due to the nature of sublimation at a temperature of 100 – 110oC, the caffeine loss is 10% when drying the tea.

Caffeine in production due to fermentation reacts with the oxidation products of Catechin to produce caffeine – oxy neonate called titanate – caffeine (mainly in black tea). This product can be precipitated at low temperatures, forming a scum on tea water at room temperature and dissolving at temperatures up to 60oC.

Tanat – caffeine gives the tea its characteristic in terms of smell, taste, and colour.

Enzym:

In tea leaves, there are two critical enzymes: redox and hydrolytic. Other groups exist in negligible numbers.

Some redox enzymes play an essential role in tea processing. Under the effect of polyphenol-oxidase, the product is thearubigin, the component that creates the colour and flavour of the tea.

Glucose in tea (in % dry matter):

Depending on the cultivar and the amount harvested, the glucose content varies more or less.

On average, there are:

-Monza: 1-2%.

-Sucrose: 0.5 – 2.5%

-Polysaccharides: 10-20%

-Starch: 0.1 – 0.3%. The older the tea leaves, the higher the amount of starch.

-Pectin: 2 – 3%.

Pigment (pigment):

The tea colour is an essential sensory indicator of finished tea. Two colourants make up the colour of tea: colours present in the starting material and colours created during processing.

The original natural pigment consists mainly of chlorofin A, chlorofin B; pheophytin A, B; carbonite, xanthin, violaxanthin, and neoxanthin. Processing, new pigments of tea are also formed. Depending on the requirements of the product, the technologist creates optimal conditions for the desired colour.

For example:

– Black tea: It is necessary to create optimal conditions for the enzyme to oxidize tannin into quinol compounds and destroy chlorine, forming a dark black colour for finished tea.

– Green tea: it is necessary to inactivate the oxidizing enzyme to keep the maximum amount of tannin and chlorine to create an “amber” green colour for tea.

Carotenoids also play a specific role in the aroma process of tea because, when oxidized, they will form aromatic compounds such as unsaturated aldehydes and ketones.

Fragrance:

Aroma is also a significant indicator of finished tea. The aroma of tea is created from 2 different sources of aromatic substances: the aromatic substances available in the original tea leaf material (essential oils) and the aromatic substances produced through the processing process.

The natural essential oils found in tea leaves are deficient in content. Through processing, several new aromatic substances are created.

From the point of view of food biochemists, aldehydes play an essential role in flavouring tea. During processing, new aromas are created due to the interaction between amino acids and simple sugars, between amino acids and tannins under high temperatures, catalyzed by enzymes, etc., often creating aromatic aldehydes. Or they are further converted to form other aromatic substances.

Ashes:

The ash in young tea leaves and the finished product ranges from 4-7%. The younger the tea, the less ash. Ash in tea consists of many different substances. Each substance is closely related to the growth of the tea plant. These substances are in the soil and absorbed by the tea plant as nutrients to feed the plant. The main imports are metals, carbon, arsenic, potassium, calcium, phosphorus, sulfur, and silicon.