Named after the process “crush, tear, curl”, CTC tea is the main type of tea in tea bags. It is made by passing leaves through a series of cylindrical rollers that crush, tear and curl them. CTC teas, which are small black pellets, have a strong flavour and are quick to infuse. CTC teas are designed to be drunk with milk, are the base for masala chai and the best qualities have an even finish (the pellets are uniform in size).
The CTC machine was invented by Sir W.G. McKercher in Assam in 1931 and more than 90% of all black tea is produced this way.
The saying “keep your friends close and your enemies closer” has always seemed like good advice to me. Given my close association with orthodox tea, on one of my trips to Kolkata I asked my friends at Jay Shree Tea if it would be possible to visit one of their CTC estates to learn more about CTC tea: the enemy.
Always willing to oblige, they arranged for me to visit the Marionbarie tea estate on the foothills of Darjeeling. At just 250 meters above sea level, the estate borders the Darjeeling garden of Long View at its lowest elevation, and is similar in appearance to a tea estate one might find in Assam. One of the similarities is that Marionbarie is planted exclusively with Assam clones. These produce brisk teas (meaning they have an astringent bitterness that sets your teeth on edge) with a dark chestnut liquor. While CTC is the type of tea most commonly drunk in the UK, the teas produced at Marionbarie are exclusively for the Indian domestic market.
CTC tea production
CTC tea and orthodox tea are not only very different in taste and appearance, but the production process is also different. When making CTC tea, it’s essential to retain the moisture in the leaf. Failure to do so will result in unevenness in the finished tea, which is undesirable in both orthodox and CTC production. The differences begin at the plucking stage. Whereas the strict rule for high quality orthodox tea is to pluck only the bud and the two leaves immediately below it, it is common for CTC tea to pluck the third and even fourth leaves.
Withering
The leaves are then plucked and placed in large withering troughs with a meshed bottom through which air is forced from the outside. This step happens on a larger scale and faster compared to orthodox tea production, as the tea maker wants to retain a much higher level of moisture in the leaf.
Crushing and cutting (tearing)
Once the leaves have reached the desired level of pliability, they are transferred to the next stage of production where the wilted leaf is cut into smaller and smaller pieces as it passes through a series of rotating cutters. As the tea is crushed and torn, the pressure causes the cells in the leaves to naturally break down.
Curling
Once the cutting/tearing stage is complete, the tiny pieces of leaf are then passed through a large rotating drum. The drum is approximately two metres deep and the leaf particles move slowly from one side of the drum to the other as it rotates. The spinning action of the drum forces the leaf to curl as the particles climb the curved sides and then fall back on themselves, creating the desired pellets.
Throughout the process, steam is pumped into the production area to maintain an ambient humidity of 90%, ensuring minimal moisture loss.
Oxidation
The pellets then move to the oxidation stage, which is a slow moving conveyor belt. It takes approximately 90 minutes for the pellets to move from one end of the conveyor to the other, depending on the ambient temperature, by which time the pellets are fully oxidised.
Firing (fixing)
The next stage is the firing, which further reduces the moisture content and thereby stabilises the tea.
Sorting CTC tea grades
The pellets are then sorted according to size, by passing through a series of vibrating sieves with a graded reduction in mesh size: The smaller the pellets, the further they fall. Each sieve has a mouth to which a sack is attached and so each sack fills with pellets and granules of varying sizes. The medium and smaller pellets achieve the best prices at auction. The medium size granules are favoured in the north of India and the slightly smaller ones in the south. The very small granules and dust are ideal for the production of teabags.