Effect of methods to remove polyphenols from sunflower meal on the physicochemical properties of the proteins

Abstract

Sunflower meal was extracted 4x with 50% aqueous acetone, 40% aqueous ethanol, or 40% aqueous methanol to remove polyphenols. The flaked kernels were also extracted 5x with water (pH 6.0) at 70 degree C. With organic solvents the efficiency of polyphenol removal was 95-98% whereas with water it was only 83%. Extraction with water and organic solvents increased protein content of the meal and decreased total sugar content. Amino acid composition of the protein did not change. N solubility of the extracted meals was lower than that of the unextracted meal in water in the range pH 2-8. However, there was no change in the gel filtration or sedimentation velocity pattern. In PAGE, methanol-extracted meal proteins had higher mobility. Between 300 and 400 nm the fluorescence emission intensity of extracted meal proteins was higher than that of the unextracted meal proteins. Extracted meal proteins were hydrolysed to a greater extent by trypsin/alpha-chymotrypsin/papain than the unextracted meal proteins.