Increasing the Amounts of Bioactive Components in American Ginseng Leaves by Using Far-Infrared Irradiation

The roots, leaves, and other parts of American ginseng contain ginsenosides and polyphenols, among other bioactive components. So far, reports on exploring the changes in bioactive components within its leaves after heat treatment have been limited. In the present study, we investigated the effects of far-infrared irradiation (FIR) heat treatment from 160 to 200 ℃ on the deglycosylation and dehydration rates of the bioactive components in American ginseng leaves. As the temperature was increased, the amounts of constant ginsenosides decreased while those of rare ginsenosides increased. After FIR heat treatment of the American ginseng leaves at an optimal 190 ℃, the highest total polyphenolic content and kaempferol content were detected, the antioxidant activity was significantly enhanced, and the amounts of rare ginsenosides F4, Rg6, Rh4, Rk3, Rk1, Rg3, and Rg5 were 41, 5, 37, 64, 222, 17, and 266 times higher than those in the untreated leaves, respectively. Moreover, the radical scavenging rates for 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), and the reducing power of the treated leaf extract, were 2.17, 1.86, and 1.77 times higher, respectively. Hence, optimal FIR heat treatment at 190 ℃ is an efficient method for producing beneficial bioactive components from American ginseng leaves.