Antioxidant capacity of phenolic extracts from selected food by-products

Potential use of blueberry leaves and canola hulls as a source of natural antioxidants was explored. Cyclone canola hulls and blueberry leaves were extracted with acetone (70%, v/v). Crude phenolic extracts were fractionated on Sephadex LH-20 column into two fractions; fraction A was rich in non-tannin phenolics while fraction B was rich in condensed tannins. The total content of phenolics in the extracts ranged from 44 to 517 mg catechin equivalents per gram of extract. Higher levels of condensed tannins were detected in blueberry leaves extracts than in canola hull extracts. The fraction B exhibited stronger free radical scavenging activity than both fraction A and crude phenolic extract.