Anhua dark Tea is a significant component of Chinese dark teas and has seen numerous breakthroughs in new product development, process innovation, and equipment advancements in recent years. This article introduces the basic situation and latest research progress regarding Anhua dark tea products and processing techniques from three dimensions: product categories, traditional processing techniques, and processing techniques.
Classification of Anhua Dark Tea Products
Anhua dark tea products available in the market can be categorized into traditional Anhua dark tea products and innovative Anhua dark tea products (Table 1), based on their production history and form.
Traditional Processing Techniques for Anhua Dark Tea
The traditional processing of Anhua dark tea involves two stages: initial processing of dark rough tea and refinement, which includes sorting, pressing, and Drying of the rough tea.
(1) Initial Processing Technique for Anhua Dark Rough Tea
The production of Anhua dark rough tea includes several steps: withering, fixation, preliminary kneading, heap fermentation, secondary kneading, and drying.
① Raw Material Requirements
The main raw materials used for making dark rough tea are local varieties such as Yuntai Mountain large-leaf, Zhuye Qi, Fuding Dahongpao, Taoyuan large-leaf, and the popular Jinhuang tea in recent years. Generally, fresh leaves with one bud and three or four leaves picked after the Grain Rain period are used. For some high-grade special rough teas, one bud and one or two leaves are selected as raw materials.
② Production Process
Fixation: Fresh leaves need to be spread out moderately before fixation. Coarse and older raw materials with lower water content require watering to increase their moisture content to ensure uniform and thorough fixation.
Heap Fermentation: After kneading, the fixed leaves are piled up for heap fermentation. The temperature of the pile needs to be controlled between 30 and 40°C. If the temperature exceeds 45°C, the pile should be turned. When the color of the tea changes from dark green to yellow-brown, the green smell disappears, and a wine-like aroma appears, the heap fermentation is considered adequate.
Drying: After heap fermentation, the rough tea is kneaded again and then enters the drying stage. Traditionally, the drying of Anhua dark rough tea uses a seven-star stove. The tea is evenly spread layer by layer on a baking curtain, with about 4 to 5 layers, each layer being around 5 cm thick. When the last layer of tea is 70 to 80 percent dry, the fire is reduced, and the tea is flipped and baked until the stems and twigs break easily and the leaves can be ground into powder. The moisture content of the tea should be 8% to 10% when it is removed from the stove. This drying method gives Anhua dark rough tea a unique pine smoke aroma. As drying technology has advanced, microwave drying and hot air drying have been applied in the processing and quality research of dark rough tea. To better meet the requirements of cleanliness and continuous operation, the seven-star stove has been gradually replaced by modern clean drying equipment like automatic chain plate dryers, which results in dark rough tea with a unique post-fermentation fragrance.
(2) Refinement of Xiangjian Tea
Xiangjian tea is a type of Anhua dark tea that has higher standards for both appearance and quality. Its processing mainly consists of three steps: sorting, blending, and pressing.
① Raw Material Requirements
For the refinement and sorting of Tianjian and Gongjian teas, black rough tea of grade one or two must be chosen. After rolling and round sieving, the tea is sorted using double-layer shakers and sifters to remove stems. It is then subjected to color selection and wind selection to sort and remove impurities.
② Production Process
Hot Kneading: The raw material of Xiangjian tea is relatively coarse and old. To improve its shape, the rough tea is usually hot-kneaded for 3 to 4 minutes after steam treatment to tighten the tea leaves into strips.
Baking: After hot kneading, the tea is baked. Once the color of the tea changes, it is flipped and mashed, and the moisture content is controlled at around 12%. The semi-finished tea is blended according to sieve number.
Pressing: After blending, the tea is pressed directly. The pressing process includes weighing, steaming, packing, compression, bundling, inserting needles, and air-drying. After the tea is softened by steaming, it is packed into baskets in batches and bound with cross-shaped bamboo strips to tighten the bundles. Then, silk grass from Anhua is inserted into the four corners and center of the bamboo package through holes made with a flower needle, allowing moisture and heat to escape from inside the basket.
Air-Drying: The pressed tea bundles are transported to a well-ventilated and dry place for air-drying. After 4 to 5 days, when the moisture content drops below 14%, they can be released from the factory.
(3) Stamping and Air-Drying of Huajuan Tea
Huajuan tea is a Compressed tea in Anhua dark tea that relies entirely on manual labor throughout its processing. Its refinement process includes weighing, steaming, packing, stamping and shaping, locking, and air-drying.
① Production Process
Weighing: The outer layer of the tea baskets used for packaging Huajuan tea is made of woven bamboo that is over three years old, the middle layer is palm leaf, and the innermost layer is dock leaf. Taking Qianliang tea as an example, to ensure the weight of the tea is 36.25 kg, the tea is weighed five times, with each weighing 7.25 kg. Following the steps of five weighings, five steamings, and five pressings, the tea is weighed in batches and then steamed.
Packing: After steaming, the tea is packed in batches into the bamboo baskets. The softened tea leaves are tightly packed into the baskets, and the top is sealed with a “bull cage mouth.”
Stamping and Shaping: After sealing, the tea column is carried to the stamping area for stamping. The stamping is done while tightening the body with a twisting rod and pressing with a pressing rod, alternating between the twisting and pressing rods.
Locking: After the stamped Huajuan tea cools and sets, the locking process begins.
Air-Drying: Huajuan tea is naturally dried under the sun during the day and exposed to the night air, a process that typically takes 49 to 52 days, with the edges turned twice and the heads turned once. Through natural air-drying, slow post-fermentation occurs until the moisture evaporates, forming the unique qualities of Huajuan tea.
(4) Pressing and Flower