Rheological nature and dropping performance of sweet potato starch dough as influenced by the binder pastes

Starch dough is a biphasic system in which the solid starch granules are dispersed in a continuous liquid matrix of binder paste. Experiencedly, the rheological nature of starch dough is vital to starch noodle production and heavily depends on the binder paste applied. The starch dough processing in the manufacture of starch noodle is widely spread but lacks scientific evidence. In the present study, the rheological behaviours of nine binder pastes and their corresponding sweet potato starch doughs were investigated by both steady shear and dynamic oscillatory shear measurements. The results showed that the processing characteristics of starch doughs were highly dependent on the binder paste applied, i.e., the doughs with binder pastes from sweet potato, cassava, potato and waxy maize starch displayed better dropping performance than that with binder pastes from pea, mung bean, wheat, rice or maize starch. Rheologically, both binder pastes and starch dough exhibit overall shear-thinning and thixotropic properties. A good binder paste could be defined by a lower thixotropy, consistency and loss modulus, as well as a higher loss tangent. For the first time, the present study performed a rheological characterization of starch dough and cast a new light on the dependence of its processing suitability on the binder paste involved. The findings herein successfully merge the experiences of starch dough processing into science.