ARS | Publication request: Antioxidant activity and phenolic content of defatted buckwheat (Fagopyrum esculentum Moench) flour in water or ethanol heated using microwave irradiation at varying temperatures

Submitted to: American Journal of Food Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 18, 2008
Publication Date: N/A

Interpretive Summary: Buckwheat is a non-cereal crop but with potential applications similar to cereal grains and is gaining interest due to its propensity to have nutritionally-beneficial higher phenolic content and antioxidant activity. Buckwheat seeds were ground and sieved to a fine flour, then extracted in mixtures of water and ethanol while being exposed to microwave irradiation at varying temperatures. Buckwheat flour microwave-irradiated in 50% ethanol had highest phenolic content at each respective temperature studied and highest antioxidant activity was observed for buckwheat microwave-irradiated in absolute ethanol regardless of temperature. This study showed a trade-off is experienced among the treatment combinations of microwave irradiation, temperature and solvent in obtaining high phenolic content and antioxidant activity and that further adjustments are needed to produce buckwheat ingredients that can improve human diets to prevent or mitigate cancer, coronary heart disease, diabetes and neurodegenerative diseases.

Technical Abstract: Buckwheat (Fagopyrum esculentum) has potential to be a nutritionally beneficial crop due to its high phenolic content and antioxidant activity. We explored new technologies to enhance buckwheat phenolic content and antioxidant activity. Buckwheat achenes were ground and flour was extracted for 15 min in water, 50% ethanol or 100% ethanol while heated at 50, 100 or 150 deg C by microwave irradiation. Buckwheat flour was also extracted in same solvent treatments at 22 deg C (not microwaved). Buckwheat microwave-irradiated in 50% ethanol had highest phenolic content at each respective temperature studied. Highest antioxidant activity was observed for buckwheat microwave-irradiated in absolute ethanol regardless of temperature, or at 22 deg C, regardless of solvent. This study showed a trade-off is experienced among the treatment combinations of microwave irradiation, temperature and solvent in obtaining high phenolic content and antioxidant activity. Microwave irradiation can obtain extracts with higher phenolic content but with similar antioxidant activity to extraction at 22 deg C.