Nano-reduction of starch from underutilised millets: Effect on structural, thermal, morphological and nutraceutical properties

Abstract

Starch nanoparticles from pearl (Pe) and proso (Pr) millets were characterised for morphological, thermal, rheological and nutraceutical properties which are important parameters to be considered for predicting applicable domain of nanoparticles in food and other industrial applications. In the present study after using collision ball milling to achieve the nano-reduction, dynamic light scattering (DLS) revealed the average hydrodynamic particle diameter of 636 nm and 417 nm for nano-reduced pearl (PeN) and proso (PrN) millet starches. Further the nano-particles produced were having greater stability, as revealed by the data obtained for zeta potential. X-ray diffraction (XRD) revealed loss of crystallinity in starch granules whereas attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) showed no difference in the basic functional groups but decrease in intensity. Scanning electron microscopy (SEM) was used to elicit the changes in surface topography of starch granules upon nano-reduction. Post nano-reduction treatment various thermal transition temperatures significantly shifted to lower values. Results of anti-oxidant assays for prediction of nutraceutical potential revealed significant increase upon nano-reduction.