2.2. Single‐factor experiments of UAE parameters

The UAE parameters of extraction time, NaOH addition, and ultrasound power were used as a single factor in this study, respectively. The fundamental UAE parameters were as follows: extraction time 80 min, NaOH addition 40 g/L, and extraction power 100 W. Three UAE extraction factors were as follows: The extraction time was tuned to 0, 40, 80, 120, 160, and 200/min; the NaOH addition was tuned to 0, 20, 40, 60, 80, and 100/ g/L; the ultrasound power was tuned to 0, 50, 100, 150, 200, and 250/W. Each process was repeated three times. The ranges of 3 UAE independent parameters have been confirmed.