EFFECTS OF SURFACTANTS ON WHEAT-PROTEIN FRACTIONATION BY FLOW FIELD-FLOW FRACTIONATION

The effects of different nonionic (Brij 35, FL-70, Triton X-100, Tween 20 and Tween 80), cationic (CTAB) and anionic (SDS) surfactants in 0. 05M acetic acid, at several concentrations, on flow field-flow fractog rams of three wheat gluten fractions were assessed. Alcohol soluble gl iadins, acetic acid soluble glutenins and sonicated acetic acid insolu ble glutenin fractions all showed optimum resolution and reproducibili ty with FL-70, Brij 35 or Triton X-100. F1-70 proved superior compared to the other two surfactants due to its lower tendency to foam, makin g buffer preparation much easier. Fractograms obtained in the presence of low concentration of other nonionic surfactants (Tween 20 and 80) and the cationic surfactant, CTAB, gave similar fractograms but resolu tion was inferior. At higher concentration, above the critical micelle limit, CTAB gave poor resolution and reproducibility. Low concentrati ons of SDS caused protein precipitation. At a higher concentration of SDS, also above the critical micelle concentration, reproducibility wa s also a problem. However, results indicated that SDS was able to rele ase lower molecular weight proteins from the larger polymeric insolubl e gluten fraction which remained bound with nonionic detergents.