Effect of different drying methods (microwave drying, shade and sun drying) on the quality of sumac fruit (Rhus coriaria L.)

In this study, the effect of microwave drying method (at five power levels: 200, 400, 600, 800 and 1000 watts) on drying time, color change, amount of organic acids and vitamin C of sumac fruit (Rhus coriaria L.) was investigated. The experiment was conducted in a completely randomized design with three replications and the response surface methodology (RSM) was used to find the optimum points for the minimum drying time and color changes or the maximum organic acids and vitamin C during drying. The results showed that microwave drying had significant effect on the color, the amount of organic acids and vitamin C at 5% probability level but it had significant effect on drying time at 1% probability level. Among the different microwave powers, the highest and lowest organic acids were obtained at 1000 and 600 watts with values of 1.46 and 1.11 mg/100 g, respectively, and the highest and lowest vitamin C was obtained at 600 and 1000 watts with values of 0.40 and 0.26 mg/100g, respectively. The best situation for microwave drying (with the lowest drying time and color variations and the maximum phytochemicals) was obtained at 815 watts. Finally, the lowest color changes and the highest amount of organic acids and vitamin C were observed in the shade drying method.