Drying of kiwi rings by osmotic dehydration and solar dryer

Osmosolar dehydration is a hybrid drying method that uses a* combination of osmotic dehydration and solar decontamination methods. In this study, kiwi fruit was sliced into rings and dried by osmotic dehydration, natural convective multi-shelf solar energy dryer and osmosolar dehydration. In the osmosolar dehydration process, kiwi rings were first immersed in sucrose solutions and then dried in a solar-powered dryer. The effect of the drying method on moisture loss, drying speed, diameter shrinkage rate and change in color parameter a was determined during the drying period. It has been observed that osmotic dehydration process is effective in drying kiwi rings with multi-shelf solar-powered systems. In addition, the response surface method was used to determine the effect of drying conditions on drying performance and to find the optimal level of drying conditions for the responses. The drying conditions were selected as kiwi slice thickness, sucrose solution concentration, immersion time and drying time in solar powered dryer. The responses to be optimized are moisture loss, diameter shrinkage rate and green color change. A successful mathematical model has been established using the response surface method. A quadratic model was chosen for moisture loss, and a binary interaction model was chosen for color change and shrinkage ratio. Model R2 values are 0.952 for moisture loss, 0.737 for color change, and 0.856 for shrinkage. The optimum drying conditions level was determined as 12.7% for sucrose solution concentration, 4.06 mmfor slcie thickness, 125 minutes for solar drying time and 70.9 minutes for osmotic dehydration time.