Microwave Drying of Grapevine (Vitis vinifera L.) Leaves and Determination of Some Quality Parameters

Grapevine (Vitis vinifera L.) leaves with 50 (+0.05) g weight and 75.35% (+0.02) humidity on wet basis were dried in microwave oven at 17, 15 ve 13 W g(-1)microwave power densities, until the humidity fell down to 9.13% (+/- 0.12) on wet basis. Drying processes were completed between 210 and 270 s depending on microwave power density levels. In this study, measured values were compared with predicted values obtained from 7 thin layer drying equations with a new thin layer drying equation and a new model is called Alibas (equation is derived from Midilli et al). In this study, within applied microwave power densities; models whose coefficient of regression (R-2) are highest and standard error of estimated (SEE), root mean square error (OKH) and chi-square (chi(2)) are lowest were chosen to be the best models. According to this, the best model at the all temperature levels was found to be Alibas model. The best quality in terms of colour and ascorbic acid values were obtained in the drying period with 15 W g(-1) microwave power density.