The effects on of the tea drying performance and color change of different drying methods in green tea production

In this study, green tea leaves were dried by using different drying methods such as air conditioning cabinet, oven, sun and shade in May and July. The best method determined according to the colour values, drying times, mathematical modeling and drying kinetics. Green tea leaves were dried with natural drying methods, sun, shade, air conditioning cabinet (30 ° C - 30% humidity, 40 ° C - 45% humidity, 60 ° C - 60% humidity at 3 different temperatures and relative humidity), oven (35 ºC, 40 ºC, 45 ºC and 50 ºC). Drying times, respectively, in the 1. drying in the sun and 2. drying in the sun, and drying in the shade 54, 59 and 121 hours, air conditioning cabinet at 30 ° C - 30%, 40 ° C - 45% and 60 ° C - 60% humidity 47, 48 and 57 hours, in the oven at 35 ºC, 40 ºC, 45 ºC and 50 ºC drying temperatures 29, 26, 25 and 22 hours. As a result of experiments, the shortest drying process was determined 50 ºC in the oven, the longest drying process was determined shade drying process. In the study, thin-layer drying models was used, like Jena Das, Midilli – Küçük, Yağcıoğlu and Modified Page mathematical models. It was determined that the best mathematical model predicting the drying curves was the Midilli - Küçük model. Fresh and dried green tea leaves, in terms of quality criteria color analysis was made, and L brightness, a redness and b yellowness values were determined. The browning values, chroma and hue angles were calculated and it was determined that these values are differentiated. The nearest values of browning index, hue and chroma to the values of fresh products were observed in the sun drying method in the 1. drying in the sun. As a resuld of the analysis it was determined that the sun and shade drying were effecting the green tea plants quality negatively, and the best suitable drying method was determined at low temperatures at oven drying method.