What is Tea?
An Introduction to Tea
Tea leaves are obtained from the evergreen Camellia Sinensis plant, grown mostly in tropical and subtropical climates. The nature processing of these leaves determines the type of tea - Black, Green, White, Oolong, etc. Processed tea leaves are steeped in boiling water to create an aromatic infusion, enjoyed by tea-drinkers around the world.
Most of the tea produced around the world is said to be Black Tea, accounting for approximately 75% of the world’s total tea production. Green Tea, known for its numerous health benefits, accounts for 20% of the total tea produced, while the remainder 5% includes the lesser-known Oolong teas, the premium White teas and the rare Yellow teas.
The Camellia Sinensis plant contains a large quantity of xenobiotics, as they play a role in the plant’s natural defenses. When included in our diet, these are digested and converted into energy along with water-soluble compounds.
Tea may appear to be a casual drink to many, but in reality, this beverage has a deep-rooted history that is intertwined with traditions around the world. Wars have been fought over tea. Till date, every cup of tea is an experience that tells a story. So the next time you brew a cup, remember to savour the unique taste notes and flavours that come with every sip.
How is Tea processed and classified?
The processing of the tea leaf is a crucial process, and plays an important role in the flavours and taste-notes of the tea. All types of tea are obtained from the same Camellia Sinensis plant and it is the processing of the leaves that determines the categorization such as Black, White, Oolong, etc. The scientific method to categorize teas based on the processes it undergoes originated in China, and has now spread to most of the tea producing countries of the world.
Tea Classification
From the single species of Camellia Sinensis, six different types of tea can be obtained:
- Black Tea
- Green Tea
- White Tea
- Oolong Tea
- Yellow Tea
- Post-fermented Tea
Modifications in the methods used to process the teas result in variations within each type of tea. Differences in the type of plant and the cultivar are some of the factors that influence the resultant tea produced.
Tea processing:
Processing of fresh tea leaves can include two to seven stages that each affect the taste, texture, colour and quality of the tea. Every added or excluded stage affects the category of tea. At every stage, the leaves are processed in controlled environments where the moisture and temperatures are monitored so as to avoid spoilage of the leaves.
Learn more about each of the main processes involved below:
Withering
This is usually the first step in the processing and involves wilting of the tea leaves. In other words the moisture content of each leaf is reduced by approximately 30% and this results in the development of the flavour compounds. It is usually carried out in controlled conditions indoors, but can also be done outdoors. Fresh tea leaves are spread on troughs, which are then exposed to heated air from below. During this process, significant changes take place in the leaf, mainly in the volatile compounds. These include changes in the level of caffeine and an intensification of flavours. If the process is carried out for a shorter period of time, the colour of the leaf tends to be greener while the flavours are mostly grassy. A longer wither produces a darker leaf with an intense and aromatic flavour.
Fixing
During this process, heat is applied to control the enzymatic browning of the withered tea leaves. It is believed that the longer the time taken for ‘fixing’, the more aromatic the tea. It is carried out using different methods - pan firing, steaming, baking or by making use of heated tumblers. Steaming results in teas with a ‘greener’ taste and vegetal flavours, as the leaves are heated more quickly, while pan-fired leaves have a toasty taste. The stage is necessary in the processing of green and yellow teas.
Oxidation
Oxidation begins right when the tea leaves are plucked due to exposure to oxygen which results in chemical reactions within the leaf that intensify the flavour. Some of the chemical compounds that begin to develop are polyphenolic oxidase, theaflavin and thearubigin. This is the process responsible for the browning of the leaves.
The level of oxidation can be controlled to affect the flavour intensities of the tea. Temperature in the controlled environment usually ranges from 25-30 degrees celcius, while humidity is controlled at 60-70%. Withering helps the leaves become softer for rolling in this process. Post rolling, the leaves are laid out left undisturbed for a predetermined time period, so that fermentation can take place. They are then heated and dried by panning.
The level of oxidation has a major role in influencing the flavour profile of the tea and colour of the liquor produced. Lesser oxidation results in greener leaves, semi-oxidized leaves are browner and make an infusion that is yellow-amber in colour, while completely oxidized leaves are blackish-brown due to a complete break down in amino acids and lipids.
Rolling
This process involves altering the physical form of the leaves. The processed tea leaves are rolled and shaped gently. After this process is carried out, the tea leaves assume a characteristic shape - tightly rolled pellets, wiry leaves or kneaded leaves. It is during the rolling that sap from the leaves and essential oils seep out, which intensifies the taste of the tea. An interesting fact may be noted about the resulting tea - the tighter the roll of the leaf, the longer it is to retain its freshness.
Drying
Drying is done at different stages during the processing of the leaves. The moisture content of the leaves is significantly reduced to less than 1% after drying. This prolongs the shelf life of the leaves and results in an enhanced flavour. The drying time and conditions are controlled using an industrial oven, in which they are roasted or fired at specific temperatures. It is important that the temperature and time are monitored during this process. If the time is too short, it will affect the taste of the leaves, making them abrasive and harsh.
Aging
Just like wine, the taste of certain types of tea improves with time. An ideal example would be the Chinese Pu-erh tea, which is aged and fermented for years before it is ready to be consumed or sold. The Chinese Pu-erh tea is an expensive tea due to the processing involved and it is savoured by tea drinkers around the world.
Orthodox vs CTC Tea
Orthodox and CTC refer to the methods of production used in India. Orthodox tea is produced using traditional processes such as withering, fixing, oxidation, rolling, drying, etc. CTC is an acronym for ‘Crush-Tear-Curl/Cut’, as the leaves are processed using modern machinery such as cylindrical rollers that crush, tear and curl the leaves using serrated blades.
The CTC method of production mainly used for commercial processing of black tea as it is a faster alternative to the orthodox method, and consistency can be maintained in the quality of the tea produced. Orthodox processing requires far more manpower than the CTC methods which are machine intensive.
In orthodox processing, the leaves are never cut nor torn apart, and are instead carefully rolled to bring out the desired flavours.
The main differentiating factors between the two methods of production and the resultant teas they produced can be summarized as under:
- Traditional v/s modern - While orthodox production uses traditional methods that may be time consuming, CTC teas are produced using modern techniques that have evolved to speed up the processing of leaves.
- Intent - Orthodox production is carried out with the purpose of preserving the virutes of each leaf. CTC production is ensure faster production while maintaining consistency in the quality of tea produced.
- Tools used - Orthodox production requires manpower as human intervention is needed at various stages. Care must be taken at every stage and the conditions must be manually controlled in order to bring out specific flavours. In the case of CTC, tea leaves are fed into machines that carry out the cutting, tearing and curling in fixed time-frames.
- Taste notes of the tea - Tea processed using orthodox methods provide a more authentic experience, and the flavours are far more complex than machine-processed teas. CTC teas produce a strong liquor, which is relatively darker in colour and exhibits an astringent flavour when tasted.