White finger millet starch: Hydrothermal and microwave modification and its characterisation

Abstract

White finger millet (WFM) starch was modified by hydrothermal (HS) and microwave (MS) methods. Modification methods had a significant change in the b* value observed in the HS sample, and it caused the higher chroma (∆C) value. The treatments have not significantly changed the chemical composition and water activity (aw) of native starch (NS) but reduced the pH value. The gel hydration properties of modified starch enhanced significantly, especially in the HS sample. The least NS gelation concentration (LGC) of 13.63 % increased to 17.74 % in HS and 16.41 % in MS. The pasting temperature of the NS got reduced during the modification process and altered the setback viscosity. The starch samples exhibit the shear thinning behavior and reduce starch molecules' consistency index (K). FTIR results exhibit that the modification process highly altered the short-range order of starch molecules more than the double helix structure. A significant reduction in relative crystallinity was observed in the XRD diffractogram, and the DSC thermogram depicts the significant change in the hydrogen bonding of starch granules. It can be inferred that the HS and MS modification method significantly alters the properties of starch, which can increase the food applications of WFM starch.