Role of Raw Material On Tea Quality

The quality of tea leaves as raw material depends on its chemical composition which inturn is determined by climatic conditions, genetic properties of the blush and agronomic practices particularly the type of  shoot harvested. In south India considering the total economy, 85% three leaves and a bud are targeted while plucking. However due to dearth of pluckers, harvesting of crop at the desired interval becomes difficult and quite often the coarse leaf component exceeds the threshold level of 10 %. Besides this, inadequate attention to leaf handling also affects the quality of tea adversely.
The types of damage on tea leaf during and after plucking.

1. Leaf Handling : Tea manufacture begins from the time the leaf is plucked. An important prerequisite for preservation of quality is the prevention of damage to the green leaf. Changes in its physical and chemical characters before processing could adversely affect the quality of the finished product. Therefore, great care should be taken while handling the leaf in the field, and during transport.
                           
                  Damage to leaf could occur either due to rough handling, bruising or heating of leaves due  to their compression in the baskets/snacks and tight packing in the bags. The damage to plucked shoots starts while plucking itself. A plucker can hold upto 80 shoots of prescribed size without any damage and when she tries to hold more than 80 shoots, they are damaged. Damage is more conspicuous when plucking interval is extended. Arranging for weighments three to four times a day and delivering the leaf as quickly as possible to the factory will be helpful in avoiding leaf damage. Plucked leaf awaiting transport to factory should not be exposed to the sun. The leaf should be loaded in the bag to a maximum of 25kg .
2. Influence of raw material on tea processing: The influence of raw material on different stages of manufacture with varying percentage of coarse leaf was studied in the UPASI mini processing unit in COONOOR.Two hundred kg each of green leaf with different levels of coarse leaf was naturally withered by applying ambient air for 15 hours, and maintaining a spread of 3 kg /sq. ft. In all the treatments the RC level was maintained at 50% and the fermentation period was 75 minutes. While drying an inlet temperature of 250 degree F was maintained.
   
   WITHERING: Percentage withering was only 82 when 50 per cent coarse leaf was used as against 65 per cent withering with 15 per cent coarse material. The moisture content in the green leaf and withered leaf was monitered. As the coarse component increased the moisture content decreased. Despite low level of moisture, after 15 hours of whitering the moisture removal was only 6 percent, when the coarse leaf composition was only 50 percent. This indicates that with normal conditions it may not be possible to achieve proper whitering, if the coarse leaf composition is high. For obtaining proper physical and chemical whiter suitable for CTC manufacture 12-15 % moisture should be removed. When the coarse leaf component is high, it is advisible to load the truff at around 2.5kg per sqft. or to increase the air flow inside the plenum chamber.
3. Biochemical Evaluation: The cuppage of tea mainly depends on total suluble solids(tss) in the made tea. The total soluble solids was higher in tea manufacture with 15% coarse composition. The briskness and the brightness of the liquor mainly depends on theaflavin content in the made tea. Generally higher the theaflavin content better will be the liquor character.