Abstract:
In this research, drying characteristics, energy requirement and colour changes of Watercress (Nasturtium officinale R.) in hot-air drying with glass cabin were reported. Samples of freshly harvested Watercress were dehydrated in three different temperatures, 50 degrees C, 60 degrees C and 70 degrees C. Selected drying air velocity was 0.65 m.s(-1) for all temperatures. Watercress were dehydrated from the initial moisture content of 390 (percentage dry basis) to a final moisture content of 7 ... 9%. The minimum specific energy requirement was determined as 25,54 kWh.kg(-1) for 70 degrees C. 60 degrees C drying air temperature was found to yield better quality product in terms of colour retention of Hunter L, a, b and Delta E. As a result, in order to reduce drying energy consumption and to keep better colour retention, this hot-air drying can be recommended for this kind of application. Drying data were modelled with 8 different drying models. Models with the highest coefficient of regression (R-2) and lowest standard error of estimation (SEE) were determined to be the most appropriate models. According to this, Aghbashlo model has been determined to be the best model at 50 degrees C, 60 degrees C and 70 degrees C hot-air drying with glass cabin in terms of the closest values between experimental data and predicted data.
