Ultrasonic Enhancement on Propolis Extraction at Varied pH and Alcohol Content

Abstract Propolis extraction using hydroalcoholic solutions at varied pH was ultrasonically enhanced in order to reduce the extraction duration. The studied parameters also involved the ethanol concentration, pH and duration. The ultrasonic enhancement consisted of 14 cycles with each cycle of 10 min of ultrasonication and 10 min of cooling down. The total phenolic and the flavonoid contents of the extract samples were determined. Within 100 min, it was found that the optimum propolis extract could be collected using the solvent with ethanol concentration of 30% and pH 10 under ultrasonication. The bioactivities of the optimum extract, such as antioxidant and antibacterial attributions, were further studied. The optimum propolis extract exhibited lower antioxidant properties compared with the propolis extract produced via maceration (24 h, 70% ethanol). However, the optimum extract that exhibited slightly greater effect toward gram‐positive bacteria was the propolis extract prepared through maceration. Practical Applications Propolis extraction is always time‐consuming and requires great amount of ethanol. This study presented the significant improvement in propolis extraction using ultrasonication, which is biochemically safe. Ultrasonication enhances the removal and recovery of active compounds from propolis matrix during extraction because the solvent has been energized. As the process time has been greatly shortened, the scale of extraction unit can also be greatly reduced. Such technique is believed to appeal to industries that seek an economical and green alternative extraction technique to produce commercialized functional food.