The optimization of extracting total polyphenols from clove based on the simultaneous ultrasonic-microwave assisted extraction (UMAE) and the analysis for its high efficiency

The simultaneous ultrasonic / microwave assisted extraction ( UMAE) technology of extracting total polyphenols from clove was optimized and the reason for high-efficiency of this method was analyzed through comparison analysis and scanning electron microscope. The results showed that the optimal parameters of the UMAE technology were as follows, the extracting time was 12 min, the microwave power was 75 W, the ultrasonic power was 50 W, the ratio of sample to extracting solution was 1 ∶30 (g∶m L) , and the concentration of ethanol was 50%. The comparative study showed that the extraction ratio of total polyphenols from clove by UMAE was significantly higher than those of microwave assisted extraction (MAE) and ultrasound assisted extraction (UAE) (p <0.01) . A comparison of scanning electron microscopy on clove powders indicated the higher extraction efficiency of UMAE results from the more serious disruption of cell structure and the more sufficient interaction.