Heat treatments of ginger root modify but not diminish its antioxidant activity as measured with multiple free radical scavenging (MULTIS) method

Ginger (Zingiber officinale Rosc.) root (or rhizome) has been reported to have antioxidant properties such as reactive oxygen species scavenging activities. Using multiple free-radical scavenging method, we have newly determined the scavenging abilities of ginger roots against five reactive oxygen species, i.e., HO(•), O(2)(−•), RO(•), tert-BuOO(•), and (1)O(2). After heating grated ginger roots at 80°C for 2 h, nearly 50% decrease in scavenging ability was recorded against (1)O(2) and tert-BuOO(•). Conversely, the O(2)(−•) scavenging ability increased by about 56% after heat treatment. Based on the antioxidant activity measurement of the ginger’s components, i.e., 6-gingerol, 6-shogaol, and zingerone, active species acting as antioxidant capacity of ginger was shown. Additionally, ginger’s antioxidant capacity was quantitatively compared with that of rosemary extract, indicating that rosemary is peroxyl specific scavenger while ginger has higher scavenging ability against HO(•) and (1)O(2).