Green tea, also known as unfermented tea, is made from suitable tea tree shoots through typical processes such as de-enzyming, rolling, and drying. Its dry tea leaves, brewed tea liquor, and spent leaves are predominantly green, hence the name. Green tea retains a large proportion of the natural substances in the fresh leaves. It retains over 85% of the polyphenols and caffeine, about 50% of the chlorophyll, and suffers minimal vitamin loss, resulting in green tea's characteristic "clear liquor, green leaves, and strong astringent taste." Scientific research shows that the natural substances retained in green tea have special effects in preventing aging, preventing and fighting cancer, sterilization, and anti-inflammation, which are superior to other types of tea.
1. De-enzyming (Killing Green)
De-enzyming plays a decisive role in the quality of green tea. High temperature is used to destroy the enzymes in the fresh leaves, preventing the oxidation of polyphenols and thus preventing the leaves from turning red; at the same time, it evaporates some of the water in the leaves, softening them and creating conditions for rolling and shaping. As the water evaporates, the low-boiling point aromatic substances with a grassy smell in the fresh leaves volatilize and disappear, thus improving the tea's aroma. Except for special teas, this process is carried out in a de-enzyming machine. Factors affecting the quality of de-enzyming include de-enzyming temperature, amount of leaves, type of de-enzyming machine, time, and de-enzyming method. These are all interconnected and interdependent.
2. Rolling
Rolling is a process that shapes the appearance of green tea. External force is used to break and soften the leaves, rolling them into strips, reducing their volume, and making them easier to brew. At the same time, some of the tea juice is squeezed out and adheres to the surface of the leaves, which also plays an important role in increasing the concentration of the tea's flavor. The rolling process for green tea is divided into cold rolling and hot rolling. Cold rolling refers to rolling the de-enzymed leaves after cooling; hot rolling refers to rolling the de-enzymed leaves while they are still hot without cooling. Tender leaves are suitable for cold rolling to maintain a bright yellow-green liquor color and tender green leaves, while older leaves are suitable for hot rolling to facilitate tight strip formation and reduce broken pieces. Currently, except for premium teas which are still processed manually, the rolling process for bulk green tea has been mechanized.
3. Drying
The purpose of drying is to evaporate moisture, refine the appearance, and fully develop the tea's aroma. There are three drying methods: oven drying, pan-frying, and sun-drying. The drying process for green tea generally involves oven drying first, followed by pan-frying. Because the tea leaves still have a high moisture content after rolling, direct pan-frying would cause them to quickly clump together in the pan, and the tea juice would easily stick to the pan walls. Therefore, the tea leaves are first oven-dried to reduce the moisture content to a level suitable for pan-frying.