How to use air conditioning to make tea green?

I. Environmental factors and their impacts

There are three main factors: raw materials, technology and environment. Among them, the environment is the most important.

(1) Influence of temperature on greening.

1. Adverse effects of high temperature on dyeing.

The green temperature affects the formation of aroma and taste of oolong tea. There are fewer kinds of aromatic substances in high-temperature enzyme fixation, but more kinds of aromatic substances in medium-temperature and low-temperature enzyme fixation. Due to the increase of temperature, the activity of polyphenol oxidase is enhanced, polyphenols are rapidly oxidized, and the formed o-quinone is unstable. O-quinone is a strong oxidant, which can not promote the oxidation of amino acids to produce volatile aldehydes, so that carotene can be oxidized and decomposed to produce various floral components, and fatty acids can be oxidized to produce aromatic and fruity aldehyde acids. The intense respiration and enzymatic oxidation caused by high temperature consume more amino acids and soluble sugars, which affects the high aroma and pure taste of crude tea.

The content of tea polyphenols in fresh leaves of summer and summer tea is high, and it takes a long time to fully transform. Reducing the temperature of green-making creates conditions for the special requirements of the transformation time of summer and summer tea contents. The enzymatic action of tea stopped below 65438 05℃. The lower the temperature, the slower the chemical reaction speed. At 15-20℃, the enzyme activation is weak and the chemical reaction is slow. Taking advantage of this characteristic, air conditioning was used to control the low temperature and low humidity environment, reduce the temperature and prolong the time of enzyme fixation, so as to meet the needs of high tea polyphenols content and long chemical transformation time in fresh leaves of summer and summer tea.

2. The adverse effect of low temperature on green.

Low temperature is not absolutely better, it depends on whether the climate is dry or humid, warm or cold. In the low temperature and rainy season in spring, although the temperature is low, the humidity is high, so it is difficult for green leaves to "walk" and the physical and chemical changes are slow. Microbial reproduction leads to discoloration and odor of green leaves. At this time, it is difficult for air conditioners to refrigerate and dehumidify, so heating dehumidification technology must be adopted to turn spring tea green, which is beneficial to increase theaflavins.

(B) the impact of environmental humidity on greening.

The aroma quality of oolong tea is obviously different under the same variety, environmental temperature and green-making process conditions and different environmental humidity. The humidity is too high, and the partial pressure of water vapor in the air is high, which inhibits the green leaves from losing water and can't "run water", which is easy to cause microbial reproduction and make tea rot. When the humidity is too low, the green leaves lose water too fast, the concentration of cell fluid is too high, the green leaves are oxidized too fast by enzyme, and the contents are not fully transformed, which is easy to cause red stems, red leaves or dead leaves.

(3) The influence of airflow on greening

Fresh leaves are still alive in the process of turning green. Breathing needs to consume oxygen and expel CO2, so that oxygen in the air decreases and CO2 increases. Therefore, there should be some ventilation in the greening room to drive away turbid air and moisture and replenish fresh air. Under closed conditions, the air rich in CO2 in the leaf layer is not fresh, which inhibits the normal respiration of fresh leaves, thus prolonging the greening time and affecting a series of biochemical changes. The air velocity of closed mesophyll is close to zero, which is not conducive to the dilution of water vapor layer on the blade surface, and makes the relative humidity of mesophyll microenvironment higher, which is still far from the environmental conditions on the north wind day.

(4) the influence of shaking force on greening

Through the mechanical action of shaking green leaves, on the one hand, the energy level of green leaves is improved, so that the contents can obtain the energy of biochemical reaction, and the transportation of water and soluble inclusions in leaf stems is promoted; On the other hand, it destroys the tight structure of leaf cells, makes enzymes combine with compounds, and promotes the transformation of green leaf contents. Shaking is the process of green leaves absorbing energy, and airing is the process of energy release inside green leaves. After repeated shaking and drying, the contents of green leaves undergo physical and chemical changes in a certain order under the induction and participation of energy, and macromolecular compounds gradually degrade into small molecular compounds.

Green leaves have less friction and collision and more exercise, which is beneficial to the astringency of green leaves. Green leaves have more friction and collision, less exercise, and leaf cells are easily damaged, resulting in enzymatic oxidation, which is conducive to inducing aroma. Therefore, it is necessary to cooperate with the three shakes to make good tea.

Second, the technical points of air conditioning greening

1. Fresh leaf raw materials

The suitable raw material for fresh leaves is 2-3 leaves per bud. Pick after noon 1 1.

Step 2 do green room temperature

Before drying, the temperature should be lowered in advance, so that fresh leaves can exchange heat quickly after entering the green room, reduce the leaf temperature and slow down the physical and chemical changes of fresh leaves. Adjust the greenhouse temperature in the range of 18-222.

3. Blade spread

Spread the dead leaves thinly on the water curtain without overlapping each other, so that the green leaves can fully contact with the air and exchange damp heat.

4. Rotating speed of vibrating screen

Summer and summer tea leaves are thin, easy to damage and turn red. The main way to shake green is exercise, followed by friction, which can promote running water and remove bitterness.

Third, other equipment of air conditioning.

(1) Installation position of air conditioner

The installation position of air conditioner affects the air distribution in the drying room, thus affecting the uniformity of temperature and humidity distribution and air quality. It is best to send air from the bottom up, put the air conditioner close to the ground, blow cold air from the bottom up, and replace the water vapor and polluted air in the leaf layer from the bottom up, so that the exhaust fan above the green room can intermittently discharge moisture and polluted air, forming an airflow movement from the bottom up.

(2) Fan

The function of the ventilator is to remove moisture and turbidity, and it is installed above the green room.

(3) Green room facilities

It is wise to sit in the green room facing south. When the wall material of green room is earth wall, the effect is best, and the surface is loose and rough, which can alleviate the humidity change of green room. In the early stage of drying, the moisture content of green leaves is high, the water evaporation rate is higher than that of air conditioning dehumidification, the humidity in the drying room is high, and the pressure difference makes water molecules enter the pores of the wall; In the later stage of baking, the water evaporation rate of green leaves is lower than that of air conditioning dehumidification, the humidity in baking room decreases, and the water in the wall returns to the air. Similarly, the ground should also use hygroscopic cement mortar or paving bucket bottom brick.

Finally, the current green shelf is too low to remove water vapor. Due to the use of the above equipment, the temperature difference between the upper and lower frames will increase, and it is best to replace it every 4 hours.

Rongcha (www.94069.com)