Effect of alkaline pH on sunflower 11S protein.

The effect of alkaline pH on sunflower 11S protein has been monitored by the techniques of ultracentrifugation, polyacrylamide gel electrophoresis, turbidity, viscosity, ultraviolet absorption spectra and fluorescence spectra· Both ultracentrifugation and polyacrylamide gel electrophoresis show the dissociation of the protein with increase in pH. Turbidity values decrease with pH while viscosity increases· With increase in pH absorbance of the protein solution increases and there is a red shift in the absorption maximum. Fluorescence quenching and a red shift in the emission maximum are also observed. Both dissociation and denaturation of the protein occur. Analysis of turbidity, viscosity and fluorescence data suggests that apparently denaturation follows dissociation.

Extractability of polyphenols of sunflower seed in various solvents.

The extractability of chlorogenic acid from defatted sunflower seed flour in water and salt solutions at different pH values and also in aqueous organic solvents was determined. It increased with increase in pH and at pH 8 in water nearly 70% chlorogenic acid was removed in a single extraction, while NaCl did not increase the extraction, and, MgCl2 and CaCl2 increased it, especially at higher concentrations. Methanol, ethanol, isopropanol and acetone, at 20% concentration in water, caused the maximum extraction of polyphenol. These organic solvents without added water were poor solvents for the extraction of polyphenol from the flour.