Oat antioxidant extraction and measurement - towards a commercial process

Oat flour has preserving properties that have been attributed to the antioxidant activity of phenolic compounds, particularly hydroxycinnamic acid conjugates. This work compares extraction methods based on methanol and propan-2-ol for the removal of oat antioxidants from milled oats. The efficiency of the extraction method was determined by measuring the concentration of total phenolic compounds and the antioxidant activity based on an oxidation reaction of β-carotene with linoleic acid in an emulsion. A novel method was also used based on the quenching of light generated from the chemiluminescence reaction between cytochrome c, tert- butylhydroperoxide (t-BHPO) and luminol. The chemiluminescence method proved to be reliable, rapid and sensitive. Both propan-2-ol and methanol extraction methods yielded oat extracts with antioxidant activity. The propan-2-ol extract contained approximately 70% of the activity measured in the methanol extract. Despite the lower yield, the industrial advantages of the latter method are discussed.