Antioxidant properties of tartary buckwheat extracts as affected by different thermal processing methods

The effects of roasting, pressured-steam heating and microwave heating on total phenolics, total flavonoids, and antioxidant properties of whole-meal flour from tartary buckwheat (Fagopyrum tataricum Gaertn.) were investigated. The total phenolics were evaluated by Folin-Ciocalteau assay, total flavonoids by aluminum nitrate colorimetric assay whilst antioxidant properties were based on free radical scavenging activity of flour extracts against hydroxyl and superoxide anion radicals, and inhibition of lipid peroxidation in vitro. This study showed that thermal treatment of buckwheat flour caused a decrease in total phenolics, total flavonoids and antioxidative activities. The changes in trend of the antioxidant activities due to the thermal treatment were positively correlated with the content of phenolics (R-2 = 0.8401-0.9909). Therefore, it can be suggested that special care should be taken when processing method is selected for the exploration of tartary buckwheat products. (C) 2009 Elsevier Ltd. All rights reserved.