Optimization of polyphenol extraction and antioxidant activities of extracts from defatted flax seed cake (Linum usitatissimum L.) using microwave-assisted and pulsed electric field (PEF) technologies with response surface methodology

Use of microwave and pulsed electric field (PEF) technologies for optimization of polyphenol extraction from defatted flax seed cake was attempted using a Box-Behnken response surface design. Polyphenols were extracted after microwave or PEF treatments using ultrasound under fixed variables of 200 W of ultrasonic power, a 70A degrees C water bath, and 20 min of extraction time. Measured responses were total phenolic and total flavonoid contents, and 2,2,-diphenyl-1-picrylhydrazyl radical (DPPH center dot) scavenging activity and ferric reducing/antioxidant power activities. Maximum yields of all responses were achieved under optimum conditions for microwave processing=5 min, a liquid to solid ratio=6, and at 644 W, and for PEF-assisted extraction for 30 V at 30 Hz with a 10% ethanol concentration, and a treatment time=10 s. Under optimized microwave or PEF processing conditions, yields of polyphenols from defatted seed cake were maximized.