Determination of the effect of ultrasound pretreatment application in drying of carrot and potato

In this thesis, carrot and potato samples of different slice thickness (2 and 4 mm) were dried by subjected ultrasound pretreatment at different times (0, 20 and, 40 minutes). Drying was carried out in a modified oven at temperatures of 60 and 70 °C and air velocity of 1 m/s. Drying kinetics of carrot and potato samples were formed, and ten mathematical models were applied to experimental data to select the best thin-layer drying model in drying processes. The effect of ultrasound pretreatment on drying time and rate, color, rehydration, pH, and water-soluble dry matter (°Brix) values of carrot and potato samples were investigated. Drying times decreased with increasing temperature, decreasing slice thickness and applied ultrasound pretreatment time in all drying conditions of carrot and potato samples. As a result of statistical evaluations, it is determined that Midilli et al. model are the most suitable model to explain drying kinetics of carrot and potato products in all drying conditions. While the highest rehydration ratio value in carrot samples were seen in 2 mm thick samples which are pretreated with 40 minutes ultrasound application and dried at 60 °C (6,930), the highest rehydration ratio value in potato samples were found 4 mm thick samples which were pretreated with 40 minutes ultrasound application and dried at 60 °C (2,856). As a result of drying process, b * (yellowness) values of carrot and potato products decreased. The lowest pH and °Brix values were observed in carrot and potato products in fresh products (p<0.05). As a result, it has been found that ultrasound technology can be used as a suitable method for reducing drying time of agricultural products and preserving quality parameters in convective drying process.