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ction to free caffeine from the tea matrix. Water is also used as solvent for decaffeina-tion purposes. The following steps are involved in the process: () the moisture content is increased from 1% to 4%; () the tea is treated with an organic solvent for 1 to 1 7 Nagalakshmi to extract 9% of the caffeine; () the tea is steamed with live steam to remove all residual solvents; and () excess moisture is removed by drying (1, . 3.3.1 Solvent Decaffeination Technology 3.3.1.1 Sample Screening Raw material with low caffeine content, 2%3%, is preferred. Particle size, bulk density, moisture content, and soluble solids are also important. Leafy grades, fannings (brokengrade), are good since they do not form lumps in both the extraction and steaming steps. 3.3.1.2 Sample Preparation/Conditioning of the Leaf Prewetting of the leaf is done by adding extra moisture to the leaf and allowing it to stand for 1 . Normally 1% to 4% extra moisture is added. 3.3.1.3 Extraction The optimal ratio of puried solvent to material has to be xed in column extraction, which is batch operation and requires 6- to 8- contact time. Both cocurrent and countercurrentextractions are carried out in order to achieve higher yield. 3.3.1.4 Steaming After the solvent is drained out completely, the leaf is steamed for nearly 3 min to ensure the recovery of solvent that is held in the leaf. 3.3.1.5 Drying Drying is done at low temperature (7 Ct o8 0 ) for period of 1 . 3.3.1.6 Residual Solvent in Manufactured Decaffeinated Tea The general procedure of residual solvent methylene chloride or ethyl acetate determina- tion consists of distilling of the solvent and its estimation by the gas-chromatographictechnique. The tea sample, with added methylene bromide (MB) as an internal standard, is equilibrated for 1.5 at 1 in aqueous sodium sulfate, before manual head space sampling. Methylene chloride (MC) and MB are separated on column (porosil ) at 1C and detected by an electrolytic conductivity detector