Abstract
Studies have been made of the effects of surfactants on the apparent viscosity of waxy corn starch (WCS) pastes, and the intrinsic viscosity and transparency of WCS solutions. The viscosities of the pastes and solutions, and the transparency of the solutions were increased by the addition of all anionic surfactants used, with the exception of sodium caprylate, in order of sodium caprate < sodium laurate < sodium dodecyl sulfate < sodium dodecylbenzene sulfonate. They were markedly increased by the addition of cationic surfactants, stearyltrimethlylammonium chloride and cetyldimethylbenzylammonium chloride. The surfactants which increased the intrinsic viscosities of the solution increased also the viscosities of the paste and the transparency of the solutions. The amphoteric (lysolecithin) and nonionic (Tween 60 and sucrose fatty acid ester) surfactants had little effects on the viscosities of the paste and solution. The increase in the apparent viscosity of the paste by sodium dodecyl sulfate was depressed by adding nonionic surfactants, Tween 60 and sucrose fatty acid ester. It was concluded from these results that the surfactants with the appropriate lengths of hydrocarbon chains interact with the outer branches of WCS and the interaction of WCS with anionic and cationic surfactants leads to a further expansion of the swollen granules and dispersed starches due to an electrostatic repulsion between adjacent branches of amylopectin molecules, which may result in the increases in the viscosities of the pastes and solutions, and the transparency of the solutions.
