Black tea, one of the six tea species, is the fully fermented variety. It is renowned for its red liquid. The basic production procedures of black tea include withering, rolling, fermentation, and drying. Among them, fermentation is the most significant process of making black tea. It defines the quality of the tea. Fermentation is a key process in many health products that helps seal in the benefits. It's one of the reasons why black tea appeals to the health conscious.
Making process of black tea: withering, rolling, fermentation, drying and sifting.
- The Appearance
Normally black tea is made into strips or granular shapes. Forming the two shapes requires the fresh tea leaves to be in the same state. The leaves must be tender, thick, covered with plenty pekoe so it can remain fresh for a long time. Meanwhile the color should be glossy yellowish green or vivid green. Large leaf species and medium leaf species are best suited for making black tea. The appearance is tight and thin, full of pekoe with an abundant of buds that are dark and glossy. On the other hand, large leaf species are better for making the granular shape. The dry tea is evenly shattered, looks glossy, without any mottle.
- Fresh Tea Leaves for
Making Black Tea
Black tea's quality is not only connected to the plants species, but also closely related to the environment and planting methods. Mountain areas are ideal environments for growing tea for a number of factors. Usually high mountain areas have cloudy and wet weather, fluctuating temperatures from day to night as well as fertile soil. Ultraviolet rays in these areas are higher than other areas. The UV rayscan help nitrogen produce and accumulate in the leaves. Therefore the amount of protein, amino acid and chlorophyll in fresh tea leaves will be increased but cellulose's growth will be slowed down. Thus the leaf and bud will be softer and can retain its freshness for longer. It can be used to make beautiful strips and granular shapes. Dry tea's blossom is glossy and presents a taste and has an aroma higher quality. However, tea gardens in hilly area and flat area can also be adapted to produce plant tea trees of high quality. This is dependent on choosing a good tree species and cultivating a suitable man-made condition for its growth, quality fertilizer is also key.
|Fresh Tea Leaves for Making Black Tea
|Large leaf species
||Medium leaf species
|Large and soft leaf with thin cuticle
||Thick cuticle, tough and brittle leaf, performs good in stress resistance
|Proportion of palisade to spongy is 1:2 or 1:3.
||Proportion of palisade to spongy is 1:1 or 1:1.5.
|Contains larger amount of tea polyphenol and caffeine. Dry tea has strong flavor, abundant nutrition and can be infused many times over.
||Higher amount of carotene and lutein, which can release aromatic substance. Thus small leaf species can produce not only nutritious dry teas but also highly aromatic teas
The Making of Black Tea
Withering is the most basic process of making black tea. It involves evenly removing water from the fresh tea leaves. As the water is running off, cell sap of the leaf will become concentrated, resulting in a change of the leaf's state. This process can control the speed of physical change as well as chemical change in the tea leaf in a controlled manner.
A fresh tea leaf is composed of 75% of water. If the leaves are rolled without withering, theyare easily broken and hard to be shaped into strips. Also the cell sap will be lost quickly, which impacts on the dry tea's quality. Therefore fresh tea leaves must be withered, in order to remove water and reduce the tension of fresh cells, thus the leaf will be softer and tougher, providing a better condition for rolling and shaping.
Three Main Methods of Withering When Making the Black Tea
Currently there are three ways of withering: sun withering, indoor withering, and withering using a Trough.
Put the fresh leaves outdoors under the sun. The heat from the sunlight will release the water in fresh leaves. This method is fast, easy to apply and requires no fuel. However a drawback is that it's dependant on weather conditions.
In case the weather doesn't allow for withering, indoor withering is another effective method. Set several withering shelves in a room, then put the bamboo trays carrying the fresh leaves on the shelves. At normal room temperature and a proper process, the leaves will wilt naturally. This method does produce tea leaves of good quality.
Withering using a Trough
The Withering Trough is a manually controlled machine that can wither the tea leaves with heat. The machine has a blast engine that blows hot air across the leaves. The hot air can provide enough heat to evaporate water; which takes moisture away from the leaves. Consequently, this method can solve the problem of being reliant on sunny weather conditions. A highly skilled worker who understands the process can produce the same quality tea as those that are derived from natural withering.
The Function of Rolling
The significance of rolling is on the forming of Black Tea's quality and appearance, especially strip-shaped tea. Rolling will break the leaf cell and can push out cell sap, promoting the enzymatic oxidization of polyphenols. This is what brings about Black Tea's aroma, color and flavor. Rolling determines the strip shape of Black Tea, the leaves shrink during rolling, these are then twisted into tight thin strips. As the cell sap is squeezed out to the surface, dry tea leaves will become a dark glossy color. Soluble substances rolled in leaves are easier to be dissolved, increasing the density of tea liquid.
De-agglomeration: An Important Process in Rolling
Lots of heat will be produced during rolling, especially in summer and autumn, which strongly affects the rolling. The excess heat must be released in order to control the speed of oxidization of polyphenols. Accordingly, de-agglomeration intends to lower the heat in the leaves.
Fermentation: The Secret of Black Tea
Fermentation of black tea is a series of chemical changes prompted by enzymes during the making process. It mainly refers to the oxidization of polyphenols process. Fermentation is the key process determining Black Tea's quality. It promotes the oxidization of polyphenol in the tea leaf with the help of enzymes; meanwhile other chemical substance will change. Altering the leaves from a green to a red color. This is where the unique aroma and flavor ofBlack Tea comes from.
Five significant factor in Fermentation
- The proper temperature for fermentation is usually 2 – 6℃ higher than normal room temperature, sometimes even a greater difference is required. 30℃ is best temperature for fermentation; therefore the room temperature should be between 24 – 25℃.
- Results from an experiment at The Hunan Tea Research Institution prove that high humidity is better for fermentation. When humidity is at 63% - 83%, motley spots and dark shades in the leaves can increase the percentage by up to 25% - 32.5% in tea leaves; while humidity rises to 89% - 93%, they will decline to 16% - 18.6%. Consequently, the fermentation room should be kept in humid condition. Ideally it should be at 95% humidity or higher.
- Keeping the fermentation room ventilated provides sufficient oxygen for chemical changes, as well as removing the carbon dioxide produced during fermentation. It's normal practice to install an exhaust fan on the wall of the fermentation room, or to keep opening the door or windows to let fresh air in.
- When the leaves are ready for fermentation, they will be laid in bamboo trays and be put in the fermentation room. Yet how the leaves are laid out will affect the ventilation of fresh air and the temperature of the leaves. If the leaves are laid too thick, they will be lack of fresh air and be warmed up quickly; on the contrary, if the leaves are laid too thin, they will lose heat easily. The leaves are usually laid in the thickness of 8 - 10 centimetres. It's a very precise process but we strive for the best results.
- Fermentation begins with the rolling. After the process has started fermentation will take 3 - 5 hours in spring due to lower temperatures. In summer and autumn, fermentation only takes2 - 3 hours because of the heat.
The quality of Green Tea depends primarily on using good tea leaves. The natural quality of the leaf, including color and aroma, must then be preserved during the manufacturing process. In Sri Lanka, this involves controlling the temperature to 93.2-96.8 F (34-36 C) during rolling, drying, and storage. Since tea leaves can generate their own heat, cool air is blown into the bottom of the container to keep the leaves at the correct temperature during storage. Every care is taken at every stage, to ensure the quality of our teas are not compromised.
The Governing body for green teas also subjects all exported tea to a strict inspection. Standard samples, which are established at the beginning of the tea season each year, are used to compare various properties of the finished product with the samples. Leaves, stems, moisture, content, flavor, taste, and color are all rigidly examined. There is also a stringent chemical analysis to determine tannin, caffeine, vitamin, and mineral contents. Tea is exported only after passing these tests. So you don't just have to take our word for the high quality of our teas, it's proven.
When the right amount of aeration (fermentation) has occurred, the leaf is dried in a desiccator or 'firing chamber' at 99-104˚C (210-220˚F) to prevent further chemical changes. This shrinks and darkens the leaf, resulting in the product known as Black Tea. This completes the actual manufacture.
The size of the leaf particles in your teapot bears no relation to quality per se, but it does affect the colour and strength of the brew. Manufactured tea is graded by leaf size using a mechanical sifter. Leaf grades contain the largest pieces, Broken grades are successively smaller, while the smallest grades of all are known as Dust. The larger grades tend to command higher auction prices.
To ensure consistency of appearance, flavour and quality, each grade of a particular consignment is thoroughly stirred up and mixed together. After this, the tea is bulk-packed – either in the traditional wooden chests (in former times these were lined with lead) or in more modern aluminium-lined paper sacks.