The main purpose of rolling, in terms of physical aspects, is to curl the soft withered leaves, so that the final tea can obtain beautiful strands.
When rolling, the cell walls of the tea leaves are crushed, and the tea juice is released, which is rapidly contacted with oxygen and oxidized. Therefore, in terms of chemistry, the function of rolling is to make the tannins contained in the leaves, through the peroxidase, to touch the coal and cause oxidation. Therefore, there is no clear boundary between the chemical changes in kneading and fermentation, only the degree of oxidation is different.
Some of the heat generated during kneading is caused by friction, but most of it is caused by leavening. The heat generated is especially inappropriate, as it will accelerate the oxidation of tannins. If the leaf temperature exceeds 82 degrees Fahrenheit, the resulting tea will contain tannins with a higher degree of condensation, which will reduce the color and taste of the tea soup; therefore, rolling the leaves should be done. Keep cool.
The color of the tea soup is proportional to the degree of fermentation, and the degree of fermentation depends on the amount of tea juice released during tea leaves rolling process. The greater the pressure and the longer the time during kneading, the greater the number of leaf cells broken and the deeper the brokenness, and the more the tea juice is released, and the deeper the degree of fermentation.
The method of rolling depends on the variety, climate, altitude, withering and the desired tea soup:
Variety: The worse the variety, the heavier the rolling required.
Climate: Climate conditions affect the growth of tea trees, and as a result, affect the aroma and taste of tea, so the rolling should also change accordingly.
Altitude: In places with high altitudes, the aroma is more pronounced, the temperature is lower, and it is lightly rubbed or rubbed for a short time.
Withering: If the withered leaves contain a certain amount of water, and the texture and softness of the tea leaves are consistent, the rolling method does not need to be changed. However, during the pruning period, tea trees of different varieties and climatic conditions are picked, and the results of wilting and carving are affected accordingly, so there must be some changes in tea rolling machine use.
Tea soup: If you want a tea soup with more aroma, the kneading should be light and the time should be shorter. If you want a strong tea soup, the kneading time should be longer and the pressure should be heavier. Above all, the kneading time and pressure should be determined according to the mid-winter season and the desired purpose.
From the above, the factors that affect the rolling are so different, so we can only provide the principles to help the tea maker to test by himself and find the method suitable for the special situation.