A spin-label study on lipids in dough formed at various concentrations of oxygen.

Abstract

The effect of oxygen on wheat flour lipids during dough mixing was investigated by analysis of the lipid composition and by an ESR technique with a fatty acid spin-label (4, 4'-dimethyloxazolidine-N-oxyl derivative of 5-ketostearic acid). Dough was prepared in the presence of the spin-label under an atmosphere of air, nitrogen, 95% nitrogen-5% oxygen or oxygen, and the gluten was obtained by washing out the starch. ESR spectra of the spin-label incorporated into the gluten showed decreases in the order parameter, rotational correlation time and activation energy for rotational viscosity with increasing atmospheric oxygen concentration. During dough mixing in oxygen, oxidation of lipids proceeded and bound lipids slightly decreased. These data indicate that modification of lipids by incorporated oxygen leads to an increase in their fluidity and to a decrease in their hydrophobic interaction with protein in dough.