Effect of hot-air drying on the physicochemical properties of kaffir lime leaves (Citrus hystrix)

The effect of hot-air drying namely drying time (3-15 h), drying temperature (40-80°C) and loading capacity (0.5-2.0 kg/m2 ) on the physicochemical characteristics of kaffir lime leaves was optimized using Response Surface Methodology. Twenty treatments were assigned based on the second- order CCD including 6 center points, 6 axial points and 8 factorial points. The quality of dried kaffir lime leaves was evaluated by determining moisture content, water activity, texture (brittleness) and Hunter L, a, b values. The results indicated that the most significant (p<0.05) hot-air drying conditions that affect the physicochemical properties of dried kaffir lime leaves were the main effect of drying time and drying temperature as well as the quadratic effects of the independent variables. The overall optimum conditions that resulted in desirable dried kaffir lime leaves, were achieved when the drying time was 4.9 h, the drying temperature, 60°C and loading capacity 1.4 kg/m2.