Investigation of the effect of ultrasonic pre-treatments and different drying methods on the mass transfer parameters of quince fruit drying

In this research, the thin slices of quince fruit pre treated by ultrasonic bath and probe methods (in three levels of 10, 20 and 30 minutes) and then the samples were dried using three drying methods including hot air (at three levels of temperature), microwave (at three levels of power), and freeze drying. In all treatments, mass transfer parameters including effective coefficient of moisture diffusion, convective mass transfer coefficient, constant drying rate, lag factor, non-algebraic root and Biot number were calculated by Dinser and Dost method. The results showed that the variation of effective coefficient of moisture diffusion using ultrasonic probe pretreatment was from 44.274E-8 to 110.884E-8, 72.317E-8 to 201.893 E-8 and 7.663E-8 to 11.112E-8 for hot air, microwave and freeze drying methods, respectively. These values for ultrasonic bath were 41.652E-8 to 104.369 E-8, 59.270E-8 to 183.813E-8 and 7.210E-8 to 9.829E-8 for hot air, microwave and freeze drying methods, respectively. Also, the results showed that the trend of drying rate changes was increased with increasing pre-treatment time, but the lag factor, non-algebra first root and Biot number had a downward trend. The overall results from the study of mass transfer data showed that the use of 30 minutes ultrasonic probe pretreatment and microwave drying method could produce the highest amount of mass transfer during the drying process of the fruit.