Tea Technology From Sun-Drying in Shang and Zhou Dynasties to Steaming in Tang and Song Dynasties

Introduction

In previous articles, we have discussed the era of raw tea consumption and the era of processed tea. During those times, ancient ancestors regarded tea as either food or herbal medicine. Fresh tea leaves were perishable and typically consumed immediately or boiled for consumption. Tea processing techniques began to take shape during the Shang and Zhou Dynasties. It was during the reign of King Wu of Zhou that officials responsible for tea leaves were appointed, primarily for ceremonial and funerary purposes, as recorded in the “Book of Documents” under the section “Command of the King.” To meet the requirements of ceremonial offerings, methods for the long-term preservation of tea leaves were sought. The simplest approach involved sun-drying, leading to the earliest form of sun-dried tea, which bears a resemblance to today’s white tea. Later, it was discovered that sun-dried loose tea tended to lose its aroma easily. Consequently, people began grinding dried tea leaves into powder or forming them into tea cakes, tea bricks, and tea flakes. Thus began the long history of tea processing.

Steaming Green Tea: A Major Leap

During the Three Kingdoms period, the earliest documented record of tea processing can be found in the “Guangya,” which mentions the practice of making tea cakes between the Jing and Ba regions. The leaves were made into cakes, and the sap was extracted from aged leaves after cake formation. Similarly, historical records from the time of Emperor Taiwu of Northern Wei mention the production of tea cakes in the Shu and E regions, where residents would make tea cakes, dry them, and crush them into fine particles for consumption with water. These records indicate that people were consciously processing and preserving tea leaves during that time. It also suggests that tea cake production had already emerged in tea-growing regions such as Hubei and Sichuan. Tea cakes, as mentioned earlier, involved a process of compression and natural drying. Before consumption, they were roasted, crushed, and seasoned. These advancements during the Wei, Jin, Northern, and Southern Dynasties represented significant progress in tea harvesting methods and brewing techniques. From the time of the Three Sovereigns and Five Emperors to the Three Kingdoms and the Jin Dynasty, tea evolved from being consumed raw or chewed to being boiled and consumed as part of meals, then to sun-drying for preservation, and eventually to the production of tea leaf cakes. These developments laid the foundation for the large-scale development of tea during the Tang and Song Dynasties. During the Tang Dynasty, it was observed that sun-dried tea leaves always retained a grassy aroma that was difficult to eliminate. After numerous experiments, it was discovered that steaming the tea leaves once greatly enhanced the flavor. This led to the emergence of steamed green tea, known as “qing,” marking the first significant leap in tea processing techniques. Lu Yu’s “Classic of Tea” provides a detailed account of the steaming process: “Pick it on a sunny day, steam it, crush it, pat it, bake it, pierce it, seal it, and let the tea dry.” The emphasis was on steaming the leaves before compressing them into cakes, with a small hole pierced through to string them together during the drying process. Although steaming green tea successfully reduced the grassy aroma, the high temperature caused excessive extraction of tea polyphenols and catechins, resulting in a bitter and astringent taste. To address this, the steaming process was modified by applying pressure to squeeze out some of the tea juice before forming the cakes, reducing bitterness. Furthermore, it was discovered that washing the tea leaves after steaming facilitated rapid cooling and helped retain the fresh green color, resulting in a visually appealing final product. This tea-making method became popular during the Song Dynasty, as discussed in Emperor Huizong of Song’s “Great View of Tea,” which evaluated the merits of this technique.

Conclusion

The rapid innovation in tea processing techniques reflected the prevalent tea-drinking culture of the time. If the tea culture of the Tang Dynasty can be characterized as “poetry, painting, tea, and qin,” elevating tea to an art form, then the tea culture of the Song Dynasty can be described as “firewood, rice, oil, salt, soy sauce, vinegar, and tea,” making tea an essential part of daily life. Tea-drinking culture became deeply ingrained among various social classes in the Song Dynasty, and tea-related activities permeated everyday life. As Li Jing, a poet from the Northern Song Dynasty, said, “Tea is not ancient; it originated in the lands south of the Yangtze River, spread throughout the world, and has influenced recent times. It is on the lips of both the noble and the common, and whether rich or poor, no household is without it.”

In terms of tea processing techniques, the Song Dynasty inherited the tradition of tea cakes predominant in the Tang Dynasty, but with more exquisite and luxurious craftsmanship. Particularly, during the reign of Emperor Taizu of Song, a type of tea cake called “Dragon and Phoenix Cakes” reached the pinnacle of artistry. However, in terms of technique, although steamed tea cakes eliminated bitterness by removing tea juice, the natural flavor of the tea leaves was compromised. To solve this new challenge, a new processing method emerged, involving steaming the leaves and then directly drying them without rolling or compressing. This marked the transition from steamed tea cakes to steamed loose tea. The continuous innovation in processing techniques also influenced the perception of tea consumption. By the mid-Song Dynasty, the utensils for boiling water and brewing tea changed from “cauldrons” to “pots,” and the practice of “steeping tea” evolved into “infusing tea.” Overall, although there were several innovations in the steaming tea process, the challenge of retaining aroma remained unsolved until the emergence of pan-frying techniques, which not only marked the second qualitative leap in tea processing techniques but also laid the foundation for the six major categories of tea.