A Discussion on the Withering Technique in White Tea

The production method of white Tea is natural and straightforward, consisting of only two steps: “withering – drying.” “Spreading out” refers to laying out the fresh tea leaves thinly to cool down, lose water, and dry evenly. This process has the function of “withering” as defined by modern tea-making science.

There are different understandings of withering, which I summarize as being the key to the style of the initial processing of tea. Withering involves spreading the fresh tea leaves uniformly under certain temperature, humidity, and oxygen conditions. This allows the fresh leaves to breathe naturally after being detached from the plant, extending their vegetative life. It moderately promotes the activity of enzymes in the fresh leaves, allowing for appropriate physical and chemical changes in their internal components. The fresh leaves lose some of their moisture, reducing their water content, making the stems and leaves soft and pliable for processing. This reduces bitterness and astringency, breaks down astringent substances, improves palatability, and removes grassy odors. It also makes the aroma mellow, highlights floral fragrances, and gradually develops fruity aromas, fully showcasing the aroma of the tea variety.

Freshly picked tea leaves have a high water content of up to 75% to 80%. Although separated from the plant, they remain vigorous and continue aerobic respiration, producing more heat. If this heat cannot be quickly dissipated, the fresh leaves will undergo intense fermentation under anaerobic, high-temperature, high-humidity conditions. Therefore, freshly picked tea leaves should be spread out immediately and thinly to avoid piling too thickly.

Depending on speed and degree, withering can be divided into “light withering,” “moderate withering,” “heavy withering,” and “ultra-heavy withering” and “ultra-speed withering.” Generally, the first three types of withering are used. When making Yunnan white tea, I found that its withering is much heavier than that of other teas. This ultra-heavy withering is what gives the tea its distinctive black-and-white appearance and its sweet, mellow taste with a rich fruity aroma. This type of ultra-heavy withering is widely applied in actual production in Yunnan.

Ultra-heavy withering occurs after the vegetative life characteristics of the fresh tea leaves have completely disappeared and when the water content is moderate. The cell walls and membranes rupture, releasing cellular fluids, which then overflow within the tea leaves, leading to aerobic fermentation or oxidation. Despite the seemingly unchanged appearance, intense reactions are taking place internally.

The cellular fluids gradually oxidize, causing the backside of the fresh leaves to turn yellow, red, and eventually black, while the surface covered in fine hairs dries out and turns white and shiny.

In regard to the withering of white tea, based on years of practical experience, I present a table (see Table 1) to invite further discussion.

Solar withering (or sunlight withering) typically takes place under conditions of high water content, high temperature, high oxygen levels, and strong direct sunlight, resulting in extremely rapid changes. Therefore, the duration should not be too long, and the thickness of the spread-out fresh leaves should not be too thin or too thick. The thickness of the spread-out fresh leaves should be adjusted according to the weather on the day. Compared to other forms of withering, solar withering can be classified as “ultra-speed withering” due to its rapid rate of change. It softens the fresh leaves quickly and produces noticeable external effects. However, due to many uncontrollable factors, it is difficult to manage effectively in practice, and the results are not always ideal. As a result, its application has decreased in modern times. However, the method of directly combining withering and drying remains in use.

When solar withering and solar drying are combined, attention must be paid to the thickness of the fresh leaves to prevent them from undergoing anaerobic fermentation under conditions of high temperature, high humidity, and strong direct sunlight. This production method, which relies primarily on the sun and combines withering and drying, utilizes readily available resources to produce tea. From a developmental perspective, this method likely existed historically. However, whether such tea should be categorized as “white tea” or “sun-dried Green Tea” requires further discussion. Logically, this production method may have existed before the advent of the “kill-green” technique. Modern “sun-dried green tea” fully employs the kill-green technique, so if categorized as such, it would belong to the category of “primitive sun-dried green tea.”

Having understood the mechanism of withering and the factors influencing it, people gradually moved from accidental discovery to deliberate action, transforming the uncontrollable into the controllable. They began artificial withering, using human intervention to regulate the process. Depending on the situation, they might apply heating, humidifying, ventilation, oxygenation, and various modern technological measures to control the process, even creating extreme ultra-speed withering under special circumstances. Withering may well have been one of the earliest processes in the systematic understanding of tea production.

Humidifying withering is uncommon and mostly appears in the production of Yunnan white tea, where it is used as an adjustment or corrective measure in specific regions under exceptional circumstances.

Excerpted from Pu'er Magazine

“The Natural Beauty of Craft”