Tea Manufacture
Elements vital to quality tea manufacture - from withering to the final firing process. Discover the intricate journey of tea leaves as they transform through traditional and modern manufacturing methods, each step carefully controlled to produce the distinctive character of Ceylon tea.
Manufacturing Methods
Orthodox Manufacturing
The traditional Orthodox system uses twisting rollers in a carefully controlled program. The freshly plucked leaf is taken to the lofts and spread carefully into the withering troughs. The withered leaf when ready is fed down a shute to the rollers below.
From the Dhools various grades can be extracted dependant on pressure & programme. From the Fermenting tables the oxidised leaf is sent to the drier or driers for final firing. Tea production is complicated and the tea-maker learns his craft over many years.
CTC Manufacturing
There is a modern form of production that first appeared in the 1960's, particularly in Africa. CTC (Cut, Tear & Curl) is a long conveyor system with 2 to 4 cutting boxes situated along its length. The cylinder cutter has punched teeth which rip and tear at each cutting box macerating the leaf as it progresses.
The system is an aggressive ripping action and can create heat very quickly if management is not tight. It is used in many blended teas and cheapens the resultant teas. Ceylon produces only 5.9% of total production using this method.
Elements Vital to Quality Tea Manufacture
Historical Evolution of Withering Systems
The first picture below, is of the old hessian shelved tat system which made it extremely difficult to get any control on the withering of the leaf.
Old hessian tat withering system
Modern withering process in action
The second picture shown below is of the Experimental shed erected at Le Vallon Group in 1961 to carry out the trials with Mr. Redlich of the Tea Research Institute (T.R,I) at Talawakele for the new Woods Trough Withering system before it was accepted and in particular before the Insurance company would accept these troughs being installed in the factory lofts, to replace the hessian shelving system. By December 1962 I had completed 208 trial runs.
Experimental shed at Le Vallon Group for Tea Research Institute trials - 1961
The third here is of two of the Woods withering troughs installed and working in a factory loft. This is now the standard system for withering the leaf for either the traditional rolling system and also for the Rotorvane or the Cut Tear and Curl (CTC) not that the curl is very evident. Certainly one of the modern advances that has proved to be a huge advance on the old hessian tat System.
The Woods withering troughs installed in a factory loft
Traditional Rolling Systems
Manufacture is the most important phase of all in quality production, once the disciplines have been followed in the field. The night before the receipt of the following days leaf the tea-maker will assess which fields the divisions are sending in and what yields that they anticipate. In a six division estate, he will be receiving at least 6 fields of new leaf and 6 of old field leaf.
Traditional tea rolling process
The field work history of each of the fields will be known to the tea-maker. Whether they are Assam jat (a large fleshy leaf), China jat (a small tough leaf) or a mixture of both types of leaf, whether it is rainy season leaf or dry season leaf and finally whether the field is a newly planted field or perhaps just recovering from pruning. All this will determine his rolling programme and the pressures applied, plus the length of fermentation.
Base of a traditional roller with curved 'crescent battens and a fadeaway cone' for twisting the leaf
The picture above is of the curved battens in the base of the Traditional (Orthodox) roller and it's central cone which twist the withered leaf as it is pressured down onto this bed. The type of batten or cone could be interchanged and this altered the manufacture. The central cone is attached to a heavy brass door that is dropped down to allow the leaf to fall into a trolley so that it can be taken to the Roll Breaker for the leaf to be cooled and a Dhool to be extracted.
Traditional rollers in line, nearest being charged with leaf from withering loft above - Swings in an elliptical motion
After rolling, the tea undergoes oxidization (often called fermentation), a crucial step where the leaf develops its characteristic color and flavor.
Tea oxidization (fermentation) process
Modern Manufacturing Systems
Temperature Control in Rolling
In the dry periods fermentation can take 35 minutes to 3 hours and in wet periods heat will be applied which will affect leaf quality. Rolling produces friction which creates heat, an enemy of quality tea production. Thus it is wise not to continually go down the route of excessive runs particularly with Rotorvanes.
Actual examples from a Traditionally rolled batch:
Room Temperature: 60 ° F
After one roll: 83 ° F
After Roll Breaking: 70 ° F
A modern Rotorvane system with conveyor
In the flavoury districts like Uva manufacture can take place after midnight to try and use lower temperature in the rolling rooms, helping the management of the volatile oils expressed during rolling which can easily evaporate and be lost.
Rotorvane Processing
Close-up of the double mincing chambers - wet mashed leaf exiting
Roll breaking is when the dhool (batch) is discharged from the roller and passed over the roll breaker which has a vibrating sieve. The leaf that passes through the sieve is accepted as the first dhool & sent to the fermentation process. The leaf that passes over the sieve is sent to the next roller for further conditioning.
Final Processing - Drying
A fluidised bed drier
Present day policy in the factories using traditional rollers to develop large grade loose teas, tends to favour a four roll programme especially for the larger grades or in the Rotorvane system, a two roll programme, followed by two rotorvane passes to produce maximum levels of BOPF and BOP grades.
The drier operates at 180 to 200°F and arrests the fermentation process, as well as lowering moisture level ideally down to about 2 or 3% which is ideal for keeping the tea and should never be exceeded. Over 5% and the leaf loses its sheen and becomes dull and grey looking as well as losing quality.
Quality Testing and Evaluation
Professional tea testing and quality evaluation
Professional tea tasters evaluating the final product
After the manufacturing process is complete, professional tea tasters evaluate the tea's appearance, aroma, and flavor profile to ensure it meets the high standards expected of Ceylon tea.
Historical Production Data (1960s)
With the traditional twist roller system we were only able to turnout 1,730 lbs of made tea per day. This was achieved with a 3 roll system using Jackson 36 inch & 28 inch rollers.
7,481 lbs
3,660 lbs (49% loss)
1,732 lbs (23% outturn)
77%
Manufacturing by Elevation
Use 2 traditional rollers with 275 kilos each rolling for 30 minutes, followed by 15 inch rotorvane system. The Rotorvane machines can have either one 15 inch or two 8 inch rotorvanes.
Expected Grade Outturn:
Usually using traditional twist rollers at 36 RPM with Crescent A type batten. Tea-maker applies low pressure initially, increases to full in 2nd & 3rd rolls, reverting to half pressure on final roll.
Grade Distribution:
Focus on large grade teas with larger B.O.P. grades using larger mesh sizes. Roller speeds set lower at 32 RPM with Crescent B type batten. Rolling lasts 20 minutes with lower pressures.
Speciality Grades:
Character and Market Preferences
The predominate character of low grown teas is a combination of some dryness on the palate combined with a caramel or honey sweet taste to the brew. These teas are in great demand from the old CIS countries, the Middle East, Japan and to some extent Germany.
I suppose I would compare trying to bring back appreciation of 'Real Tea' - teas that have been crafted in a season at a single estate - to the Renaissance of craft beer and cider making in the United Kingdom in recent years as against the commercial product from the large companies in their vast factories.
Summary of Manufacturing Systems
All theoretical programmes start with 10,000 kgs of green leaf with a 42-44% loss in weight after withering. The Fluidised Bed Drier (FBD) has an output of 270 kgs of leaf per hour. Medium & low elevation driers have an output of approximately 250 Kgs per hour.
Finally it can be seen that the low country relies heavily on traditional rollers, the mid-country still has a predominance of Traditional rollers but also has some factories operating on CTC & rotorvanes. The high grown areas have moved to using both systems of manufacture, with estates retaining flexibility of machinery and not travelling down one specialised route.
The manufacture comments above with regard to seasonal quality production, apply to black teas and green teas can be made at any time of year when there are a few days of reasonable dry weather. Research shows that black teas have slightly higher antioxidants than green teas, but both teas are equally beneficial for the human system, working in different ways in the human body.
Source: I am grateful to Mr. Harish Wanasinghe who provided me with notes on the present factory practices. These notes have been sourced and written by Robert Wilson of Robert Wilson's 'Ceylon' Tea and are the opinions of him and those he has contacted in the industry.
Types of Tea Manufactured in Sri Lanka
All teas are produced from leaves of the plant Camellia Sinensis. The different types of tea produced in Sri Lanka represent various processing methods and specializations within the tea industry.
Orthodox Black Tea represents 87% of Sri Lanka's tea production, emphasizing the country's commitment to traditional quality manufacturing methods that preserve the natural character and complexity of Ceylon tea.
Orthodox Black Tea Manufacturing Process
Complete Manufacturing Flow
The Orthodox method follows a precise sequence of steps, each carefully timed and controlled to produce the highest quality Ceylon black tea with distinctive character and flavor.
Complete Orthodox Black Tea Manufacturing Process Flow Chart
Orthodox Black Tea Grading Process
After drying, the manufactured tea undergoes a sophisticated grading process using various mesh sizes and mechanical sifters to separate different particle sizes and create distinct grades with specific characteristics.
Complete Orthodox Black Tea Grading Process Flow Chart
The grading process uses mesh sizes from #4 (largest) to #30 (finest) to create up to 18 different grades, each with distinct characteristics suitable for different market preferences and brewing methods.