Abstract
The effect of black cumin extract (BCE) on the physicochemical properties of rice (RS), chickpeas (CP), and sweet potato (SP) starches was investigated using a rapid visco-analyzer (RVA), a Brookfield viscometer, a texture analyzer, and light microscopy. Starch was gelatinized in BCE as is and at pH 5 or pH9. Compared to the control, the RVA data revealed that the peak, setback, and final viscosities of all three starches were reduced due to BCE as is. Brookfield profiles confirmed the increase in shear stress at higher shear rate indicating the system's pseudoplasticity (n<1). The activation energy (E-a) of CP starch in distilled water was higher than RS and SP, but SP cooked in BCE had the highest E-a indicating more temperature dependency. In general, it can be concluded that BCE has changed the properties of the starches, particularly by decreasing viscosity, setback, and pseudoplasticity. The hardness of the starch gels and the starch swelling power were reduced as well.