Ultrasound-assisted isolation, quality characterization of finger millet (Eleusine coracana) starch, and comparison with conventional isolation methods

Starch has many applications in the food and pharmaceutical industries. Finger millet is an underutilized cereal crop and a potentially viable source of starch. The conventional methods of starch isolation result in contamination and starch degradation. Developing a better process with improved starch quality is essential. Ultrasound-assisted isolation was optimized for ultrasound treatment time, power density, and solid-to-solvent ratio with the best desirability function for various dependent parameters. The optimum power density (0.07 W/cm³), treatment time (15 min), and flour to solvent ratio (1:6) increased the yield and purity to 61% and 88%, respectively. The finger millet starch yield of ultrasound-assisted isolation was higher than distilled water, alkaline, and sodium bisulfite soaking methods by 35%, 12%, and 26%, respectively. The other functional parameters of starch, such as water solubility and water-binding capacity, also improved during ultrasonication. The ultrasound-assisted isolation could be adopted for bulk processing of finger millet for starch production.