Effect of Extraction Conditions on the Recovery and Potency of Antioxidants in Oat Fiber

The inhibitory activities toward the lipoxygenase action on linoleic acid were quantified and compared from different fractions derived from oat fiber. Based on these findings, a suitable procedure that yields a fraction with the high inhibitory activity was developed. The unit operations of the procedure involve alkali aqueous extraction followed by pH adjustment and separations of insoluble fiber particles from soluble extracts. The inhibitory activity was most effectively extracted into the solution using an extraction media with pH 10. By relowering the pH of the alkali aqueous extract, the inhibitory activity could be collected as a precipitate. Such a fraction comprised 7.2% of the fiber dry matter. Compared to the untreated oat fiber, the inhibitory activity was purified 17-fold and the yield of the activity was 125%. Such a fraction had high protein (88% w/w) and lipid (12%) contents, whereas the carbohydrate content (3%) was low.