At present, matcha powder mainly includes green tea powder and black tea powder. Their processing techniques are briefly described as follows.

1. Processing principle of green tea powder

Green tea powder is processed from fresh tea leaves through techniques such as spreading, green protection treatment, withering, rolling, dehydration and drying, and ultrafine grinding. The key to its processing technology lies in how to improve chlorophyll retention rate and form ultrafine particles. During the processing, special green protection techniques are first applied when fresh leaves are spread, followed by high-temperature withering to destroy the activity of polyphenol oxidase and retain the polyphenol compounds, forming a green tea flavor. Finally, ultrafine particles are made using ultrafine grinding technology.

The quality characteristics of green tea powder: delicate and uniform appearance, bright green color, high aroma, rich and mellow taste, and green soup color. Ultra fine green tea powder is similar in taste and aroma to regular green tea, but its color is particularly green and the particles are particularly fine. Therefore, the processing principle of ultrafine green tea powder is mainly reflected in two aspects: how to use green protection technology to prevent chlorophyll damage, form green color, and apply ultrafine crushing technology to form ultrafine particles.

① The formation of emerald green color: The bright emerald green color of dry tea and the emerald green color of tea soup are important characteristics of the quality of ultrafine green tea powder. Its color is mainly influenced by the composition, content, and proportion of colored substances contained in the fresh tea leaves themselves and those formed during processing. During the processing of green tea, due to the significant destruction of chlorophyll a and relatively less chlorophyll b, the color gradually changes from green to yellow as the processing progresses; During the processing, the magnesium atoms in the molecular structure of chlorophyll are easily replaced by hydrogen atoms due to the influence of humidity and heat, resulting in the magnesium oxidation of chlorophyll and a change in color from bright green to dark green. Therefore, in order to process ultrafine green tea powder with high chlorophyll retention rate, an effective combination of green protection treatment and optimized processing technology must be adopted. At the same time, tea gardens can be used for shading treatment and fresh leaf materials of high chlorophyll tea tree varieties can be selected for production.

② Formation of ultrafine particles: Fine particles are another important characteristic of the quality of green tea powder. After processing fresh leaves into semi-finished products, the plant fibers of dried tea are broken and the leaf flesh is crushed to form particles by external force. Due to the fact that tea is a plant-based material with a high content of cellulose, attention should be paid to:

a. Tea must be dried. Generally, dry tea has a moisture content of less than 5%.

b. Choose the appropriate method of external force application. The degree of tea pulverization varies depending on the external force acting on it. Currently, the main methods used are wheel grinding, ball milling, air flow pulverization, frozen pulverization, and straight rod hammering. By generating physical effects such as shear, friction, and high-frequency vibration on the tea leaves, the tea plant fibers and mesophyll cells are torn apart to achieve ultrafine pulverization. Research has shown that the use of a straight rod hammer for tea crushing is most suitable.

c. Control of material tea temperature: In the ultrafine grinding process, as the tea leaves are crushed, the material temperature continues to rise, and the color will turn yellow. Therefore, the crushing equipment must be equipped with a cooling device to control the temperature of the material. The tenderness and uniformity of fresh leaf raw materials are the material basis for the quality of ultrafine green tea powder. The raw materials for processing green tea powder are generally suitable for spring and autumn tea fresh leaves. According to research by the Tea Research Institute of the Chinese Academy of Agricultural Sciences, the chlorophyll content in fresh leaves used for processing green tea powder should be above 0.6%. However, in summer, fresh tea leaves have low chlorophyll content and a strong bitter taste, making them unsuitable for processing ultrafine green tea powder.

Green tea powder processing steps: fresh leaves are spread for green protection treatment → steam withering (or drum withering), one leaf is crushed into pieces (drum withering is used, this process is not required) → rolling → block screening → dehydration and drying → ultrafine grinding → finished product packaging.