Scientists perfect instant tea processing
The invention is said to cut processing time by 15 hours, making it
considerably less labour intensive and reducing costs.
Developed by the Indian Institute of Technology, Kharagpur, West Bengal, the technology uses green tea leaves and buds, instead of the usual process of using manufactured black tea. The process is also said to produce a more distinct aroma as well a full flavour.
The method involves extracting the liquor from the processed leaves, tea wastes, or undried fermented leaves, concentrating the extract under low pressure, and drying the concentrate to a powder by freeze-drying, spray-drying, or vacuum-drying it.
The steps involve obtaining freshly plucked green tea, crushing the leaves, extracting the juice and subjecting it to oxidation for an hour in a controlled chamber at a temperature of 30-35°C.
After the oxidization process new compounds are formed, and the green juice turns coppery brown. The fermented or oxidized juice is then steamed and centrifuged to arrest fermentation and to remove the colloidal and suspended materials.
The next step is to dry it to obtain instant tea. The residue of the leaves can then be subjected to fermentation and drying for manufacturing black tea, minimising on waste and contributing to further cost savings.
Prof. H. N. Mishra, who headed the development of the technology, said, "Fresh tea leaves contain about 75 per cent moisture. This extra moisture means that the leaves are easier to process, which in turn helps to speed up the time and adds to the quality of the tea".
The scientists estimate that the cost of the technology is just about Rs. 1,00,000/- (€20,000). The institution had already received a patent for the process and is about to implement the technology at two Banglore based tea companies.
World tea production has been dominated by Asian countries with China, India, Sri Lanka, Indonesia and Bangladesh. China was the largest producer where output was about 861,000 million tonnes in 2004 followed by India and Sri Lanka with 850,500 and 303,000 million tonnes respectively.