Production of nanoparticles from resistant starch via a simple three-step physical treatment

The purpose of this study was to physically process Hi-maize 260® granules and investigate the size reduction towards obtaining starch nano-particles, stable in aqueous suspensions. We developed a novel sequential three-step physical process consisting of hydrothermal gelatinization, nano-precipitation and ultrasonic treatment. Ultrasonication proved to be a key-step to dismantle the ununiform agglomerates nanoparticles produced by the nanoprecipitation of the hydrothermally gelatinized starch, furnishing uniform nanoparticles (170 nm). This was unveiled by complementary Dynamic Light Scattering (DLS) and electrophoretic mobility (Z-potential) studies, as well as fluorescence spectroscopy. Notably, this 3-step process reduced the size of the starch particles to nano dimensions without destroying their crystallographic structure, as shown by X-ray diffraction (XRD) and Small Angle X-ray Scattering (SAXS), or changing. their chemical integrity, as validated by Fourier transform infrared spectroscopy (FTIR) and Thermogravimetric Analysis (TGA) analyses. Finally, we evaluated the hydrophobicity of the isolated nanoparticles by employing the sessile drop method, witnessing an increment to the hydrophobicity as a result of size reduction. Collectively, we developed a handy protocol enroot to reduce the size of RS2 starch particles enabling its application in an array of meaningful real-world food applications.