3.1.3. Effect of Extraction Temperature on the TFY

There is no doubt that temperature is a significant factor influencing the extraction yield. Hence, in order to obtain the optimum extraction temperature, UAE processes were performed at 40, 50, 60, 70, 80, and 90 ◦C, respectively, and the results were shown in Figure 1c. There was a significant increase in the TFY (varying from 2.09 ± 0.07% to 4.41. ± 0.05%) with increasing extraction temperature from 40 to 60 ◦C. However, at higher extraction temperature (more than 60 ◦C), the TFY declined. One of the possible reasons for this was that the structure of the flavonoids was destroyed under high temperature [33]. Thus, 60 ◦C was selected as the optimal extraction temperature.
