Impact of Inlet Drying Temperature in Endless Chain Pressure Dryers on the Quality Characteristics of Leafy Type of Tea Produced Using Different Leaf Standards

This study was carried out to investigate the appropriate higher inlet drying temperatures in Endless Chain Pressure (ECP) dryers to assess the improvement of quality characteristic of Orthodox type of tea of seven grades (OP, OP1, PEKOE, FBOPF, FBOP, FBOPF1 and OPA) produced using three different standards of leaves. Selected Leaf standards were 40%, 50%, and 60% of good leaves (fine plucking of two leaves and a bud). Two different drying temperatures, 205 0 F as the control and 230 0 F as the treatment, selected for this study. Pilot scale Orthodox rollers with a capacity of 15 kg withered leaves were used to undertake Pure Orthodox manufacturing process. Experiment was conducted in triplicate for each leaf standard at two different drying temperatures. Dried tea samples were separated into seven grades namely OP, OP1, PEKOE, FBOPF, FBOP, FBOPF1 and OPA. Graded tea samples were organoleptically assessed for their liquoring properties such as infused leaf color, liquor color and strength, quality and the appearance of graded tea by professional tea tasters‟ in Colombo. Results revealed that there was no significant difference in liquoring properties of made tea produced at higher drying inlet temperature against dryer temperature of 205 0 F for three different standards of leaf. It indicates that higher inlet drying temperature does not influence the overall quality of the liquor. However, a trend was observed that tea produced with 60% good leaves, gave better liquoring properties at 205 0 F than the higher inlet temperature. Therefore, when there is 60% good leaves, maintaining higher inlet temperature for drying have not gained any advantage to produce tea with better liquor quality. The appearance of OPA, PEKOE, FBOP and FBOPF grades showed a significant difference when there is only 40% good leaves at higher inlet temperature of 230 0 F. The appearance of OP, OP1 and FBOPF1 grades did not show a significant difference at higher inlet temperature for all three leaf standards of 40%, 50% and 60% good leaves. Therefore, better appearance can be achieved by maintaining higher inlet temperature  of 230oF when there is  only 40% good leaves.