Effect of surfactant structure on the pasting properties of wheat flour and starch suspensions

Systematic studies were performed on the effect of the surfactant alkyl chain length (10-16 carbon atoms) and the head group charge/structure (anionic, cationic, nonionic) on the pasting properties of wheat flour and starch aqueous suspensions by means of a Rapid Visco Analyser (RVA). An excellent agreement was observed between the effect of surfactants on the onset temperature of the pasting process (PT) and the time to reach peak viscosity (t(peak)) of wheat flour and wheat starch suspensions. Moreover, a correlation was found between the effect of different surfactants on these two parameters. With the exception of the cationic surfactants (alkyl trimethyl ammonium bromides), the effect of surfactants (alkyl sulfates, maltosides, monoglycerides, and sucrose esters) was found to be strongly dependent on the surfactant chain length. Shorter chain surfactants (C10-C12) induced an earlier pasting, while longer chain surfactants (C14-C16) had the opposite effect. The effect of surfactants on PT and t(peak) of flour suspensions was enlarged when the surfactant concentration was increased from approximate to1% to 15% (w/w) on a dry starch basis.