Effects of Okara and Its Dietary Fiber on the Retrogradation and Rheological Characteristics of Potato Starch

The objective of this study is to investigate the effects of okara and its dietary fiber (DF) on the retrogradation and rheological characteristics of potato starch. DF or okara increases the syneresis, but decrease the gel strength of potato starch with the increase of concentration. Storage modulus and loss modulus of potato starch are markedly increased with a high concentration of okara or DF during temperature sweep, especially DF. Shear-thinning behavior and apparent viscosity of potato starch are increased with more addition of DF or okara. The X-ray diffraction pattern demonstrates that okara or DF does not change the type of crystal structure but significantly increases the crystallinity of the starch matrix, especially DF. Fourier-transformed infrared spectra indicate the addition of okara or DF increases hydrogen bonds in potato starch and brings in ester carbonyl from the fiber. The addition of okara and DF can alter the retrogradation and rheology characteristics of potato starch. The addition of dietary fiber (DF) or okara significantly increases syneresis, storage modulus, loss modulus, shear-thinning behavior, and apparent viscosity but decreases gel strength of potato starch. The relative crystallinity and hydrogen bonds of potato starch increase with the addition of DF or okara. image