Changes in antioxidant activity induced by irradiation of clove (Syzygium aromaticum) and ginger (Zingiber officinale)
2007
Suhaj, M., Food Research Institute, Bratislava (Slovak Republic) | Horváthová, J., Food Research Institute, Bratislava (Slovak Republic)
Antioxidant properties of clove (Syzygium aromaticum) and ginger (Zingiber officinale) irradiated by doses of 5, 10, 20 and 30 kGy, respectively, were studied in methanolic extracts of treated spices. Ability of the extracts of both spices to quench the 2,2-diphenyl-1-picrylhydrazyl free radical was not affected immediately after irradiation of clove and ginger. After a month of irradiated ginger storage, the antiradical activity gradually increased mainly at a dose of 20 kGy. Irradiation did not cause a change in the total contents of phenolic compounds in spices immediately after radiation treatment, but during the ginger storage their contents increased, mostly in ginger irradiated at 20 kGy. In both spices, irradiation caused an increase in the contents of oxidative substances, which was proportional to the intensity of radiation, but the differences slowly vanished during the post-irradiation storage of spices. The reducing power of clove and ginger remained the same as in the unirradiated samples at all used doses of radiation. Influence of storage for five months alone on the antioxidant activity of these spices was more intensive than the radiation treatment, and resulted in an increase in the antiradical activity, reducing power and contents of total phenolic compounds in ginger, and in a slight reduction of the reducing power, contents of total phenolic compounds and oxidative substances in clove.
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