Phenolic content and antioxidant activity of extracts from whole buckwheat (Fagopyrum esculentum Moench) with or without microwave irradiation

The purpose of this study was to extract phenolic compounds and antioxidant activity from buckwheat with water. 50% aqueous ethanol, or 100% ethanol using microwave irradiation or a water bath for 15 min at various temperatures (23-150 degrees C). Phenolic content of extracts increased with increasing temperature. In general, phenolic contents in microwave irradiated extracts were higher than those heated with a water bath. The highest phenolic content, 18.5 +/- 0.2 mg/g buckwheat, was observed in the extract that was microwave irradiated in 50% aqueous ethanol at 150 degrees C. The highest antioxidant activities, 5.61 +/- 0.04-5.73 +/- 0.00 mu mol Trolox equivalents/g buckwheat, were found in the 100% ethanol extracts obtained at 100 and 150 degrees C, independent of heat source. These results indicate that microwave irradiation can be used to obtain buckwheat extracts with higher phenolic content and similar antioxidant activity as extracts heated in a water bath. Published by Elsevier Ltd.