Starch Nanoparticles Based on Ultrasonication Pretreatment and Enzyme Posttreatment: Preparation, Optimization, and Biophysical Characterization

Abstract Starch nanoparticles (SNPs), due to their minimum particle size and maximum surface to volume ratio do not have starch limitations such as low solubility and digestibility. SNPs in colloidal form were enzymatically produced using enzyme of α‐amylase in combination toultrasinication technique to accomplished SNPs gelatinization. Results indicated that SNPs with smallest particle size (109 nm) and polydispersity index (0.560), and highest zeta potential (−32.16 mV) and antioxidant activity (30%) values was obtained using 2.10 mL enzyme and ultrasonication time of 69 s. SNPs in powder form were produced using obtained optimum conditions and a laboratory freeze dryer with chamber temperature and pressure of −70 °C and 100 Pa, for 24 h, and characterized Results indicated that the provided native starch had particle size of ranging 6 to 10 µm with zeta potential value of −4.50 mV, prepared SNPs powder had spherical shape and flat surface with mean particle size, zeta potential and specific surface area values of 105 nm, −26.7 mV and 4.70 m 2 g −1 , respectively. Furthermore, oil separation time for the emulsions having starch and powder of SNPs, were 43 and 297 s, respectively. While, for the sample without emulsifier (control), this time was 22 s.