THE EFFECT OF HIGH INTENSITY ULTRASOUND PRE-TREATMENT ON THE FUNCTIONAL PROPERTIES OF MICROWAVE-DRIED PEARS (PYRUS COMMUNIS)

Abstract

The objective of this study was to investigate the impacts of high intensity ultrasound (HIU) pre-treatment on the quality of microwave-dried pears. Functional properties including color and bioactive compounds (total phenolic content (TPC) and antioxidant capacity (ATC)) of microwave-dried pears at 2 power levels (100 and 200 W) with and without HIU-pretreatment were compared with the fresh pear samples. It was concluded that the TPC and ATC of microwave-dried pears treated with and without HIU pre-treatment under both power levels were decreased in comparison with fresh pears. The highest phenolic content was determined in a HIU pre-treated (20 min) and microwave-dried pear slices at 200 W. The ATC of microwave-dried pear samples at 200 W with HIU pre-treatment were found higher than those of the samples dried at 100 W. All color parameters (L*, a*, b*) were shown a significant change depending on the drying powers and application of HIU pre-treatment. The closest color values to the fresh pear samples were found for the microwavedried samples at 200 W with HIU pre-treatment for 20 min. In overall, microwave drying process was proven to be more efficient when combined with HIU pre-treatment to acquire a high-quality food product with enhanced bioactive compounds and improved color.