Study On The Ffect Of Okara And Dietary Fiber On The Properties Of Potato Starch

Food is a complex system with multicomponent coexistence and interactions. Okara and dietary fiber are popular to improve the functional properties, quality characteristics and nutritional properties of foods. In this study, okara and dietary fiber were added into potato starch to investigate the differences effects of them on the basic properties of potato starch. The differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray diffraction and microscope were used to investigate the interactions between okara, dietary fiber and potato starch. The purpose of this study was to expand the application of okara, dietary fiber in starchy food. The specific contents are as follows:(1) The transparency, freezing-thawing stability, swelling power and gel strength of potato starch was reduced by okara and dietary fiber, the retrogradation of potato starch was enhanced, the L*and b*value were increased, and the a*value of the system was reduced.(2) In the okara suspension system, the storage modulus and loss modulus increased with temperature and concentration increasing. The storage modulus and loss modulus of the okara suspension system with5%,10%and15%concentration decreased with temperature decreasing, however, the storage modulus of the okara suspension system with20%concentration had no change and the loss modulus increased slightly with temperature decreasing. In the dietary fiber suspension system, the storage modulus and loss modulus of5%,10%and15%concentrations had no change with temperature decreasing. However, the storage modulus and loss modulus of20%concentration increased with temperature decreasing.(3) Okara had no effect on the peak tempreture of potato starch in the heating process, while the peak gelatinization temperature was delayed by adding dietary fiber. The storage modulus and loss modulus of the mixtures increased with the adding amount increasing.(4) The mixtures of okara/potato starch paste and dietary fiber/potato starch paste are pseudoplastic fluid. Shear stress, viscous coefficient and apparent viscosity increased with adding amount increasing. (5) The result of differential scanning calorimetry showed that the peak tempreture of okara/potato starch mixture same to the potato starch, okara has no effect on the gelatinization temperature of potato starch. On the other hand, the peak tempreture of dietary fiber/potato starch mixture was higher than the potato starch, dietary fiber delayed the gelatinization temperature of poato starch.(6) The result of Fourier transform infrared spectroscopy showed a new peak around1740cm-1with adding amount increasing of okara and dietary fiber. The okara/potato starch mixture with40%,60%,80%and100%adding amount showed another new peak around1532cm-1, while there was no change in the dietary fiber/potato starch mixtures. Furthermore, the peaks around3500cm-1-3250cm-1shifted to the lower wavenumber.(7) The result of X-ray diffraction showed the crystalline structure was different between okara and dietary fiber. In the okara/potato starch mixtures and dietary fiber/potato starch mixtures, the peaks of X-ray diffraction were enhanced, the crystallization peak intensity of mixing system were enhanced by okara and dietary fibre.(8) Under a microscope, there is a coexistence state of morphology of okara and dietary fiber blended with potato starch before and after pasting. Okara and dietary fiber were found in the mixtures before and after pasting, which showed the physical blending is given priority to.