Effect of dhool spreading thickness on made tea quality in orthodox-rotorvane type tea processing

Abstract

Tea grades produced by Orthodox-Rotorvane type processing in Sri Lanka is popularly used for production of value added products. In order to have a fine quality orthodox tea, a severe maceration is practiced during rolling process. Due to this severe maceration, leaf oxidation will increase and control of oxidized products (Theaflavin [TF) and Thearubegin [TR)) become difficult. This will be affected by the dhool spreading thickness and aeration time. Thus, the objectives of this study were to determine the optimum dhool spreading thickness and aeration time on made orthodox-rotavane type black tea by analyzing chemical and sensory properties. After rolling of withered (43o/o MT /WL) green tea leaves, the first dhool was extracted, and spreaded at different thicknesses (2,2 1/2 and 3 inches), and was allowed for oxidation up to 3 1/2 hrs of aeration. Temperature and humidity of the aeration room was controlled and maintained. During oxidation, 250 g of dhool from each thickness was collected at every 20 minutes intervals until the maximum oxidation time, and determination of TF, TR, and sensory analysis was done after preparation of black tea. TF content of the made black tea from each thickness (2,21/2 and 3 inches) was found to be varied from 0.91-1.140/o,0.95-1.250/o,and O.93-1.19o/o respectively. According to the chemical and sensory properties, tea spreaded at 2 inches was found to have highest liquor quality and professional tea tasters gave highest price. Further, the optimum aeration time was found to be 2 hour irrespective of spreading thickness.