GB855423A - Improvements in or relating to a process for preparing a soluble tea extract in powder form - Google Patents

Abstract

855,423. Tea extracts. INREDECO Inc. March 13, 1957 [March 22, 1956], No. 8354/57. Class 129 A pure soluble powdered tea extract is made by separating the volatile aromatic substances from a hot aqueous tea extract by evaporating water from it, by stripping with steam or other suitable gas or by a combination of these means, condensing the volatile aromatic substances, concentrating the extract, mixing the two in suitable proportions and spray drying the mixture. The aromatic constituents may be removed in a distillation column, not more than 50% of the extract being evaporated. Otherwise, the aromatic constituents may be separated in a counter current stripping column by means of steam or other gas, e.g. nitrogen, carbon dioxide or a rare gas. These methods may be combined. The extract, after removal of its volatile components, may be concentrated either continuously or batchwise at between 30 and 55 ‹C. under reduced pressure or at atmospheric pressure by freezing. out. The concentration should be carried out as rapidly as possible and the final concentrate contains 40 to 60% by weight of tea solids. It should be protected from the atmosphere, e.g. by using an atmosphere of carbon dioxide or nitrogen, and cooled below 55 ‹C. As shown, tea leaves are fed in weighed portions from container 12 to extractor 10 which is supplied with water through pipe 13 at about 100‹C. Liquid extract is withdrawn through pipe 14 and the tea leaves leave through port 15. The specific weight of the extract is measured as it passes through a pipe 14 where it is filtered in coarse and fine filters 16, 17 respectively and then pumped by pump 18 through heat exchanger 19 into stripping column 20 supplied with steam from steam generator 21. Column 20 is connected to condenser 22 and the condensate therefrom is cooled in cooler 23 and then fed to storage tank 24. The stripped extract leaves through pipe 30 and is cooled in cooler 31, concentrated in evaporator 25 and pumped into storage tank 27. Weighed quantities of the extracts from tanks 27 and 24 are mixed together thoroughly and then spray dired. An example is given using countercurrent steam stripping.