Investigation of some pretreatments on energy and specific energy consumption drying of black mulberry

Massive consumption of energy in drying industry makes it a matter of challenge regarding economical aspects and limited recourses. Several methods for drying including hot air convection, vacuum, infrared and hot air convection-infrared technologies were applied in order to estimate the consumed energy during the drying of mulberry fruit. Moreover, microwave heating, chemical (ethyl oleate and potassium), mechanical (ultrasonic) and blanching (hot water) pretreatments were compared. According to the Results, maximum energy consumption was recorded when no pretreatment was performed. Microwave heating in the hot air convection-infrared dryer resulted in the lowest consumption of energy. Total energy requirement decreased with the temperature in the convection dryer res. Conversely, energy increased with air velocity. The vacuum dryer consumed the highest amount of energy which was measured to be 46.95 kWh while the lowest energy was recorded with using infrared-convective dryers. Also Experimental results showed that minimum and maximum specific energy consumption in the drying of black mulberry were associated with microwave pretreatment in IR-hot air dryer and control treatment in vacuum dryer, respectively. The minimum color change (ΔE) for drying of black mulberry was found in microwave pretreated samples dried with the vacuum dryer, yet maximum ΔE was observed in hot air dryer when no pretreatment was applied.