| An oscillatory probe rheometer was used to measure the basic rheological properties of wheat starch pastes with addition of sugars (sucrose and lactose) and whey protein isolate (WPI). For main model systems were studied including starch-water, starch-protein, starch-sugar, and starch-sugar-protein. The mixtures were heated to 85°C, and the rheological properties of the mixtures during the cooling phase and the resulting gels were measured. In general, storage modulus (G') increased as the concentration of WPI increased. However, at 25°C starch and WPI mixtures showed a lower G' than did the starch and water system. The dependence of complex modulus (G*) on frequency indicated that the starch and water system produced stronger gel than those systems containing WPI. The addition of sucrose and lactose to the starch and water solution lowered G' at 25°C and increased delta at 85°C. During cooling, the addition of WPI to the starch and sucrose system increased G' and produced a stronger gel than starch and sucrose systems alone produced. |
