Study on thin layer drying parameters of pomegranate arils in a solar-vacuum dryer

In this research a new laboratory solar-vacuum dryer was designed and fabricated to study drying behavior of pomegranate arils with heat source of solar energy. Drying of the samples was implemented at the absolute pressures of 10, 20, 40 and 60 kPa. Impact of different absolute pressures on moisture loss trend, effective moisture diffusivity, color and shrinkage of pomegranate arils, dried in solar-vacuum dryer was studied. With regression analysis of the applied models, proved that the Midilli model had supremacy in drying behavior prediction of pomegranate arils. Results indicated that with decreasing absolute pressure, drying time was decreased. Minimum drying time was related to the absolute pressure of 10 kPa. Effective moisture diffusivity of the pomegranate arils was estimated at the ranges of 3.09×10-10 to 4.13×10-10 m2/s.Total color changes and shrinkage percent of the pomegranate arils were estimated at the ranges of 17.4 to 22.1 and 67.58% to 74.45%, respectively.