Submitted to: Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/24/2007
Publication Date: 5/1/2008
Citation: Stevenson, D.G., Inglett, G.E., Chen, D., Biswas, A., Eller, F.J., Evangelista, R.L. 2008. Phenolic content and antioxidant activity of supercritical carbon dioxide-treated and air-classified oat bran concentrate microwave-irradiated in water or ethanol at varying temperatures. Food Chemistry. 108(1):23-30. Interpretive Summary: Oats, especially the hulls and bran, are high in phenolic compounds that exhibit antioxidant activity, capable of improving human nutrition by preventing cancer, strokes, coronary heart disease and neurodegenerative diseases. We seek to produce an oat ingredient with concentrated phenolic content and corresponding antioxidant activity by removing fat from oat bran concentrate using supercritical carbon dioxide extraction, and concentrating phenolic compounds by particle size separation using air-classification, and improving solubility of phenolic compounds using microwave irradiation and extracting in different levels of water and ethanol. Oat bran concentrate, with fat removed, extracted in 50% ethanol and microwave-irradiated at 150 deg C had the greatest phenolic content and antioxidant activity, and air-classification showed potential to enhance phenolic content and antioxidant activity. This study showed potential to produce oat ingredients with higher antioxidant activity that can improve the nutrition of human diets to help prevent many serious health disorders that are the leading cause of death in United States.
Technical Abstract: Oat bran concentrate (OBC) was defatted with supercritical carbon dioxide (SCD), then microwave-irradiated at 50, 100 or 150 deg C for 10 min in water, 50% or 100% ethanol, and extract pH, soluble solids, phenolic content and antioxidant activity were analyzed. OBC was air-classified into five fractions and microwave-irradiated in water at 150 deg C. OBC without SCD and microwave irradiation was extracted at 22 deg C. Most effective temperature during microwave irradiation for maximizing extraction of phenolic content and antioxidant activity was 150 deg C. Defatted OBC in 50% ethanol and microwave-irradiated at 150 deg C extracted greatest phenolic content and antioxidant activity. SCD treatment slightly reduced phenolic content and antioxidant activity. OBC extracted in water or 50% ethanol at 22 deg C without microwave irradiation had similar phenolic content and antioxidant activity than OBC microwave-irradiated at 150 deg C, but much higher levels were observed for latter heat treatment using absolute ethanol. Air-classification shows potential to enhance phenolic content and antioxidant activity.