Structural, Thermo‐Functional, and Rheological Properties of Dielectric Modified Underutilized Jicama (Pachyrhizus, spp.) Starch

Abstract

In this study, underutilized jicama starch (JS) is treated in dielectric‐heating at different power (300, 450, 600 W) and time (1, 3, 5 min), and the change in structural, thermo‐functional, and rheological properties is observed. The dielectric modification increases the water absorption (0.81–2.88 g g−1), whereas the oil absorption capacity (1.02–0.83 g g−1) and bulk density (0.52–0.39 g mL−1) are reduced as compared to native starch. Lightness (95.46–96.26) of JS non‐significantly varies with dielectric‐heating, whereas a significant effect is observed in redness (0.01–0.06) and yellowness (3.74–4.24). The apparent viscosity of all treated samples shows shear thinning behavior. All the pasting properties other than the setback and pasting temperature of dielectric treated samples are significantly (p < 0.05) decreased at higher power than control. The onset (46.50–81.67 °C), peak (64–99.23 °C), and end temperature (68.27–100.77 °C) of gelatinization transition increased, which shows better thermal stability as compared to control. The strong‐peak for the control and treated sample is observed at around 1000 cm−1 wavenumber in the Fourier transform infrared spectroscopy. The structural changes have been observed by X‐ray diffraction analysis (XRD) and scanning electron micrographs (SEM) shows shrinkage and deformation at each power and time.