Effects of Different Drying Methods on Active Components and Antioxidant Activities of Ginger Leaves

The purpose of this paper was to study the effects of different drying methods on the active components and antioxidant activity of ginger leaves. The contents of flavonoids,polyphenols,essential oil and essential oil components were taken as the active ingredient indicators. The free radical scavenging ability of DPPH·,ABTS⁺· and ·OH were taken as the antioxidant capacity indexes. The effect of freeze drying,oven drying,vacuum drying,shade drying and sun drying on ginger leaves were compared. The results showed that the contents of flavonoids,total polyphenols and essential oils decreased after drying treatment compared to fresh sample. The highest contents of flavonoids,polyphenols and essential oils of ginger leaves were obtained by freeze drying,with the values of 21.62 mg/g,1.56 mg/g and 1.91%,respectively. Meanwhile,the free radical scavenging ability of DPPH·,ABTS⁺· and ·OH were the highest with the values of 70.42%,79.65% and 63.41%,respectively. Followed by oven drying,vacuum drying,shade drying and sun drying. More than thirty components were identified in the essential oils of fresh and dried ginger leaves by GC-MS analysis. The main components were α-cedarene,isobornyl acetate,(Z) -3,7-dimethyl-2,6-octadienal and methylheptenone. All those volatiles components were clustered into the following families,which were mainly classified into six categories:Terpenes,alcohols,aldehydes,phenols,acids and ketones. In conclusion,freeze drying had the best effect on the retention of active ingredients and antioxidant capacity in ginger leaves.