Tea has a very long, colorful and rich history throughout the years. But it all started in China, thus it stands to reason that it is there that we should look for the origins of the tea and tea processing.
Tea is harvested from an evergreen shrub called Camellia sinensis, but it has some varieties (Chinese tea is made from Camellia sinensis var. sinensis as to Indian Assam teas are made with Camellia sinensis var. assamica.) Indigenous to the East and Southeast Asia region as well as India this plant can now be found all around the world.
Tea has been known through the centuries as a healing remedy for many diseases, such as infections, coronary illnesses, asthma and much more. But what does the process of getting this amazing drink include – from the fields that it is grown to the warm cup of tea we love to drink?
Even though tea comes in a great variety of tastes, aromas, and shape, the method of processing this herb is quite identical.
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- Plucking – Tea is usually harvested two times a year – during early spring and early summer and the process of gathering the leaves is usually done by hand. It is a lot rarer for machines to do the plucking as they often damage the produce.
- Withering – After they are picked a process called enzymatic oxidation starts to settle among the tea leaves. The withering is necessary for a couple of reasons. Firstly to pull out the moisture for which they are often left under the sun or in a well- ventilated rooms. It also breaks the proteins the leaves consist of into free amino acids. The drying process also elevates the caffeine quantity inside the tea and alters the way it tastes.
- Disruption – In order to speed up the process of oxidation the tea leaves are rolled, torn or crushed. This might be done in bamboo trays for gentler touch or through machines that are much more invasive.
- Oxidation – This is a very important part of the tea processing as it plays a huge role in the way the final product tastes. Oxidation or fermentation is the breaking down of the chlorophyll and releasing of tannin in the leaves. This is when they become darker.
- Fixation/ Kill-green – Kill-green is applied in order to stop the oxidation process through the help of heat. More ancient methods for fixation include steaming, pan-firing or baking. The modern technology allows this to be done in commercial rolling drums.
- Sweltering – This is a process done only to yellow teas. The leaves are left to be slightly heated (to a close to a human body temperature) for 6 – 8hours, after the kill-green is done. This is what gives the yellow tea a more delicate taste.
- Rolling/ Shaping – As the name suggests this is when the distinct rolled-leave shape is achieved. It is done either by hand or by a machine. Damaging the leave in this way allows for the tea oils to escape and give even deeper flavor to the leaves. The tea later can be also rolled into spheres or even made into brick shapes.
- Drying – There are many ways to give this final drying to the leaves such as panning, sunning, air drying and in most cases baking.
- Aging/ Curing – Some kinds of tea like the Puerh need more processing to reach their full potential. Flavored teas need more time as well, as the flavoring is sprayed over them in time or they are stored together so the tea can absorb the flavoring.
How are different types of tea processed?
Green tea undergoes a limited time of oxidation. The preparation of the leaves starts 1-2 days after harvesting (in Japan the harvesting is done in four crops – from the end of April to May, and then it is done in June, July, and September.) Weathering is used, letting the tea leaves dry under the sun on bamboo racks. In China, they use the pan-fried technique to stop the oxidation (the kill-green). In Japan, they prefer to steam the tea leaves. The time depends on the type of tea (Example: Sencha – 30 – 90 seconds.)In China shaping is done by hand, in Japan they use machines and tea must go through additional drying for 30 minutes.
This type of tea goes through a brief period of withering that can last up to three days, depending on the conditions. The best temperature for the process is 30 degrees. This kind of tea does not undergo any oxidation or rolling.
Made in a way similar to the green tea, it has some extra processing added – it is lightly heated after the kill-green (Sweltering). This extra stage gives the yellow tea its distinct color as well as the more delicate taste.
When it comes to processing of black tea leaves they are always left to oxidize to the fullest and they also go through disruption process. Done in a humid room (20-30 degree Celsius) it takes from 45-90 minutes up to 3 hours for the oxidation to sets in. The rolling stage is very invasive and is done by hand or with the help of rotorvane.
Oolong tea has an oxidation period of about 7 hours, which puts it in the group of semi-oxidized teas (in the middle of the green and the black tea). It takes 2-3 day to reach the drying stage. The most steps necessary to make this kind of tea are similar to the ones that black tea undergoes, but here the details like temperature and timing are much more precise. Oolong tea also goes through an additional baking stage.
As the name suggest those kinds of teas have a secondary fermentation that significantly changes the smell and taste of the final product. The process of microbial fermentation can take months, even years. As the leaves of this type of teas get darker, in China they are known as Dark teas.