Abstract:

Ginger flavonoids was extracted using aqueous ethanol as solvent with the ultrasound assistance. An orthonogal test involving 3 factors (i.e., ethanol concentration, extraction time, solid-to-solvent ratio) at 4 levels was employed to optimize the extraction process. Free radical scavenging ability of the extracted ginger flavonoids was evaluated in ·OH and O2 producing solutions. Its anti-lard oxidation activity was also tested. And antibacterial activity against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Saccharomyces cerevisiae was evaluated. Results showed that the optimum extraction conditions were that ginger was extracted with 40 times of 80% ethanol and treated with ultrasound for 2 h, and the yield of flavonoids was 0.75% under such conditions. The flavonoid extract exhibited ·OH and O2· scavenging ability, and inhibited the oxidation of lard significantly. Meanwhile, ginger flavonoid extract also exhibited an antimicrobial activity on bacteria and yeast.

Key words: ginger, flavonoid, ultrasonic assisted extraction, anti-oxidation activity, antimicrobial activity