Fixation is one of the key procedures in Tea processing. “Green” refers to fresh leaves, and as the name suggests, fixation involves destroying the tissues of the fresh leaves.

Tea: Why is fixation necessary?

There is an enzyme present in tea leaves. Enzymes are biological macromolecules with catalytic functions, acting as biological catalysts that can speed up or slow down biochemical reactions without changing their direction or products.

Most enzymes are composed of proteins (some are RNA), and their activity can be easily influenced by factors such as temperature and chemical environment (such as pH). Under high temperatures, the protein molecular structure of enzymes suffers irreversible damage, completely losing its enzymatic activity. The fixation process involves high-temperature measures that cause the contents of the fresh leaves to rapidly transform.

Fixation destroys the activity of enzymes, allowing the internal substances to convert into the foundation for the unique qualities of various types of tea.

The “fixation” of tea leaves takes advantage of the property of enzymes to lose activity at high temperatures, promptly halting the activity of oxidizing enzymes (especially polyphenol oxidase and peroxidase) in the fresh leaves.

The objectives of fixation in Tea processing include:

1. To use high temperatures over a short period to destroy the activity of polyphenol oxidase in fresh leaves, inhibiting the enzymatic oxidation of polyphenols. This allows the internal substances to form the color, aroma, and taste characteristics of Green Tea, Black Tea, Yellow Tea, and Pu'er tea through non-enzymatic processes.

2. To remove some of the moisture, making the leaves softer and more pliable for kneading and shaping.

3. To eliminate the grassy smell of fresh leaves and release an attractive tea fragrance.

In summary, the purpose of fixation is to destroy the tissues and structures of fresh leaves, transforming their properties, and laying a solid foundation for the unique qualities of the tea. This is both the objective of fixation and the fundamental basis for the technical measures involved in the process.