Antioxidant capacity of bioactives extracted from canola meal by subcritical water, ethanolic and hot water extraction

Antioxidant compounds were extracted from canola meal by subcritical water extraction (SWE) at 110 and 160 °C, hot water extraction (80 °C) and ethanolic (95%, v/v) extraction. The highest extract yields were obtained with SWE at 160 °C. The total phenolics contents and antioxidant capacities of extracts were assessed by the total phenolics assay (using Folin–Ciocalteu’s phenol reagent), the 2,2’-diphenyl-1-picrylhydrazyl radical (DPPH) scavenging assay, the Trolox equivalent antioxidant capacity (TEAC) method, a β-carotene–linoleic acid (linoleate) model system, and the reducing power assay. Ethanolic extracts exhibited the highest total phenolics contents and antioxidant capacities on a per gram of extract basis. Subcritical water extraction at 160 °C yielded the highest total phenolics contents and antioxidant capacities on a per gram of meal basis. Results from the total phenolics assay and the antioxidant capacity tests were significantly correlated.