Formation and characterization of starch-based spherulite: Effect of molecular weight of potato amylose starch

Potato starch spherulites (PSS) with different molecular weights were obtained by controlled enzymatic hydrolysis of potato amylose starch, followed by super-heated quenching treatment. The impact of enzymatic hydrolysis on mean particle diameter and molecular weight was observed, ranging from 355 to 57 nm. Structural and physicochemical characteristics of produced spherulites were determined using scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry and rheological measurements. Rheological analysis indicated that PSS sample was viscoelastic with shear-thinning behavior. PSS was found to exhibit weak B-type crystallinity, similarly to that in native starch. PSS_25% had a higher thermal stability with 128.5 °C melting temperature. Microstructure confirmed there were small spherulites (1-3 μm) formed with hydrolyzed amylose starch, and starch with 15% enzymatic-hydrolysis degree was more beneficial to develop spherulite. These results may be useful in development of starch-based functional ingredients applied in plant-based foods as fat replacers, structure formers, or delivery systems.