Abstract
The objective of present research was to determine the ultrasound and microwave mechanisms involved in the improvement of the drying and rehydration of black and green olive slices. Aydın Kaba variety of olive slices in 5 mm diameter were pretreated for 15 min sonication using an ultrasonic bath (32±5 kHz, 420 W). The microwave drying was conducted at 3 different power level for each sample (180, 450 and 800 W). The Peleg model was used to investigate the drying and rehydration kinetics of olive slice samples. The color properties (L*, a*, b*, C and H°) of olive slices were also evaluated in microwave dried samples. The L values of olives increased from 45.36 to 50.05 and from 38.69 to 39.80 for green olive slices and black olive slices, respectively after microwave drying at 180 W and 800 W. An increase was observed for a* and b* values from 0.71 to 0.99 and from 4.37 to 5.11 in black olive slices. While the K1 constant decreased with the increase in microwave power in both type olives in drying process, the K2 constants in the drying of black olive slices and green olive slices increased from 0.56855 to 0.84379 and from 0.68680 to 0.77682, respectively. It was concluded that ultrasound pretreatment improves the both rehydration process and quality parameters of olive slices.