#artisanalmanufacturingprocess

In the 4th stage - Fermentation, of tea manufacturing processing - the green leaf is converted to black tea. When the leaf comes out of the orthodox, rotorvane or CTC machines, it is spread out on ceramic, concrete or aluminium slabs in cool, humid air to ‘oxidise’ or, in old-fashioned tea vocabulary, to ‘ferment’. This can take as little as 15 minutes in high grown regions during the peak quality season, but may last from 30 minutes to 3 hours out of season when the air is cooler. It is at this stage that a chemical reaction takes place between the oxygen in the air and the contents of the leaf; the leaf changes gradually from green to amber to dark coppery brown and the air is filled with the tea aroma we all recognize when we brew a pot of black tea. The temperature of the leaf is maintained at around 25-30 degrees where mild acidification of the oxidised tea increases the levels of the tea theaflavins. 

Rolling, the 3rd stage of tea manufacturing processing, of the withered leaf was perfected over centuries, a process which brings out flavour in tea. Rolling assists in establishing proper conditions for enzymatic oxidisation of the flavanols by exposure to oxygen. Two different methods of rolling are available. The ‘orthodox’ rolling machines twist and press the leaf, breaking the cell walls. This ‘orthodox’ rolling evolved from the original, centuries-old, hand rolling used for tea manufacture in China, and is still the most popular method of preparing the leaf for oxidation in Sri Lanka. ‘CTC’ (cut, tear and curl) machines macerate the lead to very small particles that brew very quickly and are generally destined for use in tea bag blends.