Fixation is a critical process in the preliminary production of Pu'er Tea, which involves using high temperatures to destroy the enzymes in fresh leaves, facilitating the transformation of their internal components and changes in moisture content. The fixation process plays a decisive role in the formation of Pu'er tea's quality, and poor control can negatively impact the tea's overall quality.

The Purpose of Fixation

The main functions of fixation include:

① Rapidly deactivating the enzymes in fresh leaves, rendering them catalytically inactive and preventing the enzymatic oxidation of polyphenols;

② Utilizing thermal chemical reactions to eliminate the grassy and bitter flavors of fresh leaves, converting them into aromatic alcohols;

③ Evaporating some of the moisture from the fresh leaves, making the leaves softer and easier to roll into strands.

It is essential to achieve an appropriate level of fixation; if the temperature is too low or the fixation insufficient, or if the temperature is too high and the fixation excessive, it will not be conducive to the formation of Pu'er tea's quality.

The Most Important Process in Pu'er Tea – Fixation

The purpose of fixation is to inhibit enzyme activity and slow down the fermentation process. During the fixation process for Pu'er tea, the pan temperature is controlled at over 200°C, while the Leaf surface temperature is maintained between 60°C and 80°C. High temperatures are used to kill some of the active enzymes, slowing down the rate of change in the tea. If there are too many active enzymes with strong activity, the tea will quickly turn red, affecting its color, aroma, and flavor. Although high temperatures do kill some active enzymes, due to the large amount of water in the tea cells, enough active enzymes are preserved to facilitate the transformation of Pu'er tea. Fixation also matures the tea, reducing its raw taste, softening the leaves, making them easier to roll without breaking. Traditionally, Pu'er tea fixation is performed manually in a Wok. The stove is waist-high, with the iron wok tilted at around 30 degrees for easy stirring. Wood is used to heat the wok, which reaches temperatures above 150°C before fresh leaves are added; one batch can contain 5-10 kilograms of fresh leaves. During fixation, the wok temperature reaches 200°C, and the leaf surface temperature is continuously controlled between 60°C and 80°C. At this point, the enzymes' activity is only deactivated during fixation, not “killed.” Manual fixation requires the tea maker to have significant experience to manage the heat well and stir at a uniform and orderly frequency. An experienced fixation master can effectively highlight the advantages of high-quality raw materials.

In the past, tea farmers often had difficult conditions, using the same pot for cooking food and then rinsing it to fry tea, resulting in the smoky flavor found in many old teas. Nowadays, with the development of Pu'er tea, experienced and well-equipped preliminary processing facilities have been established on the tea mountains, responsible for the fixation and preliminary processing of fresh leaves, providing high-quality sun-dried Green Tea with stable quality for premium products.

Insufficient or excessive fixation can have a fatal impact on the quality of Pu'er tea. Insufficient fixation cannot adequately deactivate the active enzymes in the tea, nor can it effectively release the aroma compounds, resulting in a heavy grassy flavor that affects the taste during subsequent consumption. Even after later transformations, the strong grassy flavor may become slightly milder but still result in a subpar taste. Using such raw material for fermenting ripe tea leads to overly active enzymes and other substances, causing faster fermentation that is harder to control and easily leading to over-fermentation and inferior quality.

Excessive fixation can severely damage the internal substances and microorganisms in Pu'er tea, limiting its potential for transformation during storage due to a lack of internal substances, and the aroma compounds cannot be retained for long.

Only Pu'er tea with perfectly executed fixation is considered top-grade, offering significant advantages in both taste and potential for subsequent storage.