Tea Manufacture process

Process Technology
Darjeeling teas are still manufactured using old industrial techniques developed in the late 1800's. These traditional methods are collectively termed as 'Orthodox Production'. By these methods Darjeeling teas are produced without 'cut & crush' of tender tea leaves maintaining the inherent Darjeeling tea aroma. Although differing leaf varieties require intricate variations in processing, the stages undergone are uniform. With the advancement in technology the orthodox procedures are gradually being replaced by highly mechanized methods with their primary focus on yields. But in Darjeeling hills 'Quality' is the primary focus and it is never compromised with the quantity. Darjeeling tea planter is still producing the finest teas of the world using these orthodox methods with utmost attention on the process. Of late, few gardens are changed to green tea manufacture especially during the rainy season thus producing the finest quality of flavoury green teas.
	Withering: It is the first stage of tea manufacture. During withering harvested tea flush is evenly spread on the withering troughs which are normally 4 to 5 feet wide and 50 to 70 ft long. During the process hot and cold air is blown through to remove the moisture of fresh leaf to 30-40 percent which is achieved during 16 to 18 hours of period. The prime object of withering is to make the turgid leaf flaccid and prepare the leaf for next stage to facilitate rolling.
	Rolling: The withered leaf is charged in the rollers which vary in size. Normally they are 36" and 48" rollers capable of rolling 70 to 120 kg of withered leaf. The pressure is exerted on the leaf in 'open and pressure' sequence. This operation lasts for 45 minutes. During this process tea leaf is twisted as a result of repeated rolling action and simultaneously leaf tissue ruptures thus forcing out the cell-sap which spreads as a this film on the surface of the leaf. Various enzymes and their substrates come in contact and enzymatic oxidation starts at this stage. The green colour of leaf starts diminishing and brown coppery colour of leaf begins to appear.
	Fermentation: Rolled leaf is put on fermentation racks specially made of tiles, cement or aluminium. Fermentation rooms are kept clean and cold. In Darjeeling fermentation is carried out at low temperature. In hot season the air is kept humid with the help of humidifiers with less than 20⁰c hygrometric difference Optimum fermentation is adjudged by the subjective assessment of the tea maker. Fermentation period varies from 2 to 3 hrs depending on the type of leaf, degree of wither, temperature, availability of oxygen and fermenting ability of the tea flush. The time of fermentation is reckoned from the time at which rolling begins. Fermentation is a very sensitive process. Even 5 minutes time delay in adjusting the correct fermentation period is likely to deteriorate flavour appreciably. During fermentation the leaf changes colour and becomes dark coppery. A typical aroma develops at this stage. The term 'Fermentation' is a misnomer and, in fact, it is an oxidative process. Oxidation of catechin / polyphenols by the enzyme polyphenol oxidase is the main reaction of the process that imparts 'tea character' to the black tea.
	Firing / Drying: Fermented leaf is loaded onto the dryer, which comprises perforated moving trays. The dryer inlet temperature is maintained at 200 to 240⁰F. Thickness of spread, speed of trays and volume of air blown through are regulated meticulously so as to achieve the correct drying. Low exhust temperature often produces stewed teas while high temperature in the initial stages is apt to case-hardening of teas. The whole process of drying is completed within 20 to 30 minutes. The moisture content of the final product in Darjeeling teas is kept at 2 to 3 percent. Darjeeling teas are normally fired at high temperature which is considered essential for squeezing the correct balance of volatile flavoury compounds in high quality teas. During the drying process enzymes responsible for fermentation are inactivated and even after the tea is dry the maturation process continues and tea attains the mellowness a desirable character of Darjeeling teas.
	Sorting & Grading: The bulk tea is sorted on mechanically oscillated sieves. The sieve size decreases gradually from top to bottom. Thus the bigger size teas are retained on the top while the brokenm leaves fall towards the floor.