Investigation of drying conditions of lemon slices dried by microwave assisted osmotic drying method

With the realization of the effect of microwaves on water heating with electromagnetic waves, many researchers have begun to investigate the effectiveness and usability of microwaves in heating and drying. Since the heat in microwave drying directly penetrates into the food and transfers heat from the inside to the outside, the drying process takes place faster than other drying methods and saves time. The osmotic drying method, on the other hand, requires less energy than many drying methods and is an effective pretreatment method. In this study, lemon slices were dried by microwave assisted osmotic drying method and the slices were dried in a microwave oven by subjecting them to osmotic dehydration. In this study, the effects of variables such as slice thickness, solution concentration, osmotic dehydration time, microwave power level and microwave drying time on moisture loss, drying rate, diametrical shrinkage rate and color change parameters were determined. In addition, the effect of osmotic dehydration pretreatment on microwave drying was investigated. Optimum conditions are provided by optimizing the specified variables and parameters with the Response Surface Method (RSM). As a result of the trial sets designed with the response surface method, the model with the highest compatibility was the square model and the R2 values were determined as 0.9853 for moisture loss, 0.9861 for shrinkage ratio, and 0.9770 for b color change. Optimum drying conditions were determined as 120 minutes for osmotic dehydration time, 15% for solution concentration, 4 minutes for microwave drying time and 200W for microwave drying power. It has been determined that when osmotic dehydration is used as a pretreatment, it increases the product quality and shortens the drying time.