Ultrasonic-Assisted Aqueous Two-Phase Extraction and Antimicrobial Activity of Sweet Corncob Polyphenols

One-factor-at-a-time and orthogonal array designs were applied to establish for optimal conditions for ultrasonicassisted aqueous two-phase extraction of polyphenols from swe et corncob. The effects of four process parameters including acetone concentration, ammonium sulfate dosage, extraction time and solid-to-liquid ratio on the yield of polyphenols were investigated. The optimal extraction conditions were found as follows: an aqueous two-phase system formed by adding 0.175 g/mL of ammonium sulfate to 60% aqueous acetone, solid-to-solvent ratio of 1:20(g/mL), and 25 min extraction. The yield of polyphenols in extracts under these conditions was 4.41%. The polyphenols extracted from sweet corncob had significant antibacterial activity against Escherichia coli, Bacillus subtilis and Staphylococcus white.