Effect of temperature on the kinetics of phenolic compounds extraction from ginger (Zingiber officinale) rhizome using ultrasound bath

In the present study, the effects of temperatures (40-60 °C) and different times (5-60 min) on polyphenols and flavonoids extraction kinetics using ultrasound bath were investigated, and The IC50 values of DPPH free radical scavenging activity and reducing power of the extracts were calculated. The results showed that the extraction efficiency of phenolic and flavonoid compounds increased with temperature. Also, the highest yield of these compounds were obtained during the first 15 min of extraction, and after that the slope of the extraction decreased. The highest value of phenolic compounds (165.35± 47.69 and 171.13± 36.56 µg GA/g of DW of extract) and flavonoid (9.43± 0.80 and 10.35± 0.93 µg QE/g of DW of extract) were obtained at 15 min, and 50 and 60 ° C, respectively, without significant difference. Therefore, the extraction process can be divided into two stages of rapid extraction and slow extraction. Using the kinetic curves, the maximum efficiency of the antioxidant compounds of ginger rhizome can be found with the least effective time and temperature. In addition, the results showed that ultrasound has a significant effect on the extraction of bioactive compounds from ginger rhizome compared to the traditional method.