Microwave‐assisted extraction of secoisolariciresinol diglucoside from flaxseed hull

Microwave‐assisted extraction (MAE) of secoisolariciresinol diglucoside (SDG) from defatted flaxseed hull (DFH) was studied. The effects of pre‐soaking methods and extraction parameters (ethanol concentration (0–100%, v/v), microwave energy input (50–390 W), liquid to solid ratio (5:1 to 40:1, mL g−1) and irradiation time (10–330 s)) on the SDG yield were investigated. Response surface methodology (RSM) was applied to optimise the MAE conditions as irradiation time 90.5 s, ethanol concentration 40.9% (v/v), liquid to solid ratio 21.9:1 (mL g−1) and microwave power 130 W. The SDG recovery from DFH with MAE was 11.7 g SECO kg−1 DFH (on dry‐weight basis), which was significantly higher than that of stirring extraction (10.0 g SECO kg−1 DFH) and Soxhlet extraction (7.60 g SECO kg−1 DFH). Compared with stirring extraction and Soxhlet extraction, MAE showed its superiority in improving SDG yield and saving time and energy.