Alcoholic-alkaline modification of millet starch as an emerging resource to develop granular cold water swelling properties: physicochemical, morphological and rheological insights.

In this study, granular cold water swelling (GCWS) millet starch was developed using alcoholic-alkaline treatment (AAT), applied at different temperatures, amounts and concentrations of sodium hydroxide and ethanol contents. Compared to the native starch, a significant enhancement in cold-water absorption (up to 10.40 g/g) and solubility (up to 14.11 %) was observed in GCWS starches. Morphological studies revealed smooth, polygonal and spherical granules in native starch, whereas GCWS starch granules exhibited wrinkled and indented surfaces. X-ray diffraction (XRD) analysis indicated the transition of A-type polymorph in native starch to V-type one in its GCWS counterpart. Fourier transform infrared (FTIR) spectroscopy confirmed no chemical changes upon applying AAT. Pasting properties, analysed by a Rapid Visco Analyser (RVA), represented that GCWS starches began to absorb water and increase viscosity at temperatures lower than that of native starch. Texture, turbidity, freeze-thaw stability and rheological properties of GCWS starches were influenced by different AATs. Overall, the results suggest that millet starch can be considered as a potential candidate for development of GCWS starch to be incorporated in food formulations.