The Art of Tea Processing: From Plucking to Drying

Tea’s story in the West over the past century and a half is not just important to understand our relationship with tea, but also to comprehend the current market conditions. Tea is unique and distinct from other dried herbs, spices, flowers, and fruits. It has a rich history, originates from specific growing regions, and is processed differently from other agricultural products.

Tea is made from the Camellia sinensis plant, but not all teas are equal. Tea is divided into six categories: white, green, yellow, oolong/blue, black/red, and dark/fermented. The specific processing used to make each tea determines its classification. The manufacturing process involves eight key steps: plucking, sorting, cleaning, withering, manufacturing, firing/drying, sorting, and packing. The classification of tea depends entirely on the processing method used, whether it’s white, green, or dark tea.

Processing

The most significant factors that determine the taste, aroma, and appearance of tea are undoubtedly the processing techniques used. The level of oxidation in teas such as black tea and oolong tea dramatically alters their taste, aroma, and appearance when compared to unoxidized teas. The green tea steaming process, significantly affects the tea’s taste, scent, and appearance. The steaming process results in a bright and vivid green hue and a distinct grassy flavor, whereas pan-frying creates a dull green color and a roasted, nutty flavor. These processing methods differentiate tea from other items, such as herbs, spices, and other items mixed with water.

Plucking

Plucking is the method used to extract leaves from the tea plant. The technique used to pluck leaves plays a crucial role in determining the resulting tea’s taste and aroma. Plucking activates tea bushes to produce sweet sap, a combination of chemicals responsible for the unique taste and fragrance of tea. More sap produced in tea bushes produces sweeter leaves and, in turn, sweeter tea.

Tea plants are continually plucked throughout most of the year to prevent them from flowering, directing their energy towards producing the flowers and causing the leaves to become tough and brittle. Over-plucking can severely damage or kill the plant, and tea farmers need to balance their needs for promoting sweeter teas with the plant’s growth requirements.

Many tea gardens prune their plants to grow no higher than shoulder height, known as “table” growing. This technique creates beautifully trimmed rows of tea bushes that are easy for pluckers to pick. The style of growing was introduced by Buddhist monasteries as a way to honor the gift of life that tea symbolizes. Previously, tea plants were left to grow wild, resulting in a tree-like shape. Today, farmers find table growing to be the most efficient way for pluckers to collect tea leaves.

Teas made from wild tea plants still exist, but they are sold at a premium price due to the extra time it takes to pluck the leaves. Some people believe that having tea from a “natural” or “wild” tea plant is better than tea made from the controlled growth of contemporary tea gardens.

Withering

The process of withering is crucial in creating high-quality tea, as it helps shape the tea and initiates many chemical changes that contribute to its color, taste, and aroma. While all teas are withered, there are two distinct processes: physical withering and chemical withering, both of which play a significant role in determining the type of tea being made.

Physical withering reduces the leaf’s moisture content, making it more pliable and easier to handle, whereas chemical withering is a lengthier process that breaks down complex chemicals into simpler ones, adding body and flavor to the tea. Depending on the desired taste and aroma profile, the tea master may limit the amount of chemical withering or avoid it altogether, as in the case of unoxidized teas.

Rupturing/Rolling

Oolong and black tea are distinct from other types of tea because they undergo a process called “rupturing” or rolling, which breaks down the cell walls of the tea leaf and introduces oxygen to the polyphenol oxidase enzyme (PPO enzyme), starting the oxidation process. While the traditional hand-rolling method involved rubbing leaves together, today rolling machines are used to replicate the process. Black tea and oolong tea have different oxidation rates, and thus require different machinery, but both types of machines follow the same principles as the traditional method.

In the 1930s, William McKercher developed the cut, tear, and curl (CTC) process for making black tea, which involves a machine that passes withered tea leaves between two rollers with large teeth that cut, tear, and curl the leaves, accelerating the oxidation process and creating a more bitter and full-bodied tea. This process is ideal for producing high-volume, low-quality black tea and is commonly used to make tea bags in the North American market.

Shaqing

The majority of tea types undergo a firing process, referred to as shaqing or kill-green, in which the leaves are heated to deactivate the enzyme responsible for oxidation. This step is crucial in tea production and involves exposing the leaves to temperatures above 185°F (85°C) for a duration of 30 seconds to 5 minutes.

The shaqing process plays a significant role in the taste and aroma profile of the tea. However, the process is not identical for all teas, as the size and shape of the leaves vary. For example, oolong tea is fired at extremely high temperatures, sometimes reaching 400°F–500°F (204°C–260°C) and then tossed in a revolving drum for 1 to 5 minutes.

Furthermore, black and dark teas often do not undergo any shaqing because the oxidation process is stopped during the drying stage.

Drying

The process of drying is a critical step in tea production where the moisture content of the leaves is reduced to below 4-5 percent. This step not only halts enzymatic reactions (oxidation), but also ensures that the tea leaves remain shelf-stable. However, in the past few decades, tea producers have realized that rapid dehydration through ovens can lead to inferior quality teas. As a result, the drying process has evolved into a precise science, and now tea leaves are dried uniformly at a controlled rate of 2.8 to 3.6 percent of moisture loss per hour until they reach the required moisture level of 4-5 percent.

Craft

The skill and expertise of the tea processor significantly influence the taste, fragrance, and appearance of the final tea product. Timing is critical during the oxidation process, and stopping it too late or too early can have a significant impact on the quality and flavor of the tea. Interestingly, determining when to halt the oxidation process is more of an art than a science, with tea masters relying heavily on their sense of smell to guide them. Once the desired aroma is achieved, the tea leaves are exposed to high heat to stop the oxidation process. The competency of the tea master is crucial in ensuring that the tea has a pleasant taste and aroma.

While the size and moisture content of tea leaves vary depending on the region, a general consensus among tea producers is that 33 to 55 pounds (15 to 25 kg) of dried tea can be produced for every 220 pounds (100 kg) of plucked leaves by a skilled tea master.