Impact of supercritical CO2 and traditional solvent extraction systems on the extractability of alkylresorcinols, phenolic profile and their antioxidant activity in wheat bran

• A green and environmental friendly supercritical CO2 extraction method was successfully employed.
• Addition of 10% ethanol in SC-CO2 extraction yielded more ARs compared to the 100% CO2 extraction step.
• Wheat bran phenolics were analyzed using alkaline hydrolysis and liquid–liquid partitioning steps.
• Two-way ANOVA showed cultivar, solvent and interactions, had significant effects on bioactivity.

SC-CO2 and traditional solvent methods were used to extract alkylresorcinols (ARs) in wheat bran (WB) cultivars. WB soluble free, soluble conjugated and bound phenolics were separated by alkaline hydrolysis. Also, the effects of extraction solvents on antioxidant activity were investigated by using three different solvents. The HPLC results showed that the AR content was higher in acetone extracts compared to the SC-CO2. Using ethanol as a co-solvent yielded higher ARs, especially in collector-2 for hard red WB (HRWB) (57.8 mg/100g) and soft red WB (SRWB) (37.8 mg/100g). Ten phenolic acids and six flavonoids were detected in phenolic fractions which ferulic acid was the predominant and mostly found in bound fractions. Two-way ANOVA showed that cultivar, solvent and their interactions had significantly (P < 0.05) different effects on TPC, DPPH, and ORAC values. The best solvents for ORAC, DPPH, and TPC assays were acidified ethanol, 100% acetone, and 50% acetone, respectively.