Studies on the Instant Tea (Part 3):The Batch Countercurrent Multiple Contact Extraction of Roasted Tea

概要

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Concerning the extraction procedure of roasted tea, the extracting temperature, charging rate of tea, and direction of water flow were tested with a modified small apparatus of countercurrent system which was most commonly available-in the instant coffee plant. As a result of this experiment, the following procedure seemed to be suitable for roasted tea. The tea leavess was charged to the extraction cylinder with a rate of 150-170g. per litre (of cylinder space). Fresh boiling water was pumped into the first cylinder through the top inlet in which nearly exhausted tea was filled. After travelled through six cylinders, the extract was taken out from the last cylinder in which fresh tea was charged. The extract contained about 20% of tea solids and its concentration was suitable for drying. The hot water jacket around the extraction cylinder had to be kept about 80°C. during operation to keep the temperature of extract at 70°C. and this temperature condition yielded good qualities of extract. Upward circulation of water employed for extracting "Sentya" was not suitable for roasted tea, because of its smaller bulk density, roasted tea was floated up and was pressed to the top of extraction cylinder and the current of extract become very difficult.
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