Rheological Properties of Purple Sweet Potato Flour and Its Application to Noodle Product

: Purple sweet potato is a nutritious and abundantly available food crop in Asia, that it has received much attention because of its nutritional and the accumulation of anthocyanins. The functional properties and anthocyanin content of purple sweet potato flour (PSPF) were investigated. The pasting profiles of PSPF measured by Rapid Visco Analyzer (RVA) with respect to temperature, viscosity and time attributes were investigated. The pasting curve and viscosity parameters were demonstrated that final viscosity and setback were 1677.33, 817.33 mPa.s, respectively. However, it did not show peak viscosity. The flour paste of PSPF showed a shear thinning behavior of pseudo-plastic materials, the apparent viscosity decreased with increasing shear rate. The parameter values, consistency coefficient (k) and flow behavior index (n) were 0.45 Pa.s n and 0.55, respectively. In addition, the PSPF contained anthocyanin content of 2.36 mg/g dry sample. The quality characteristics and anthocyanin content of noodle substituted with different levels at 10%, 20%, 30%, and 40% were investigated. While the substitution of PSPF increased, the anthocyanin content of noodles increased from 0.48 to 1.02 mg/g dry sample. However, the PSPF had affected the lightness and texture properties of noodle products. The tensile strength and the elasticity decreased as the levels of PSPF increased from 20.54 to 16.61 g and 16.07 to 7.79 mm, respectively.