Characterization of Resistant Starch From Eleusine coracana and Evaluation of Its Prebiotic Potential

Prebiotics are nondigestible polysaccharides that feed gut microbiota, maintaining host-gut microbiota symbiosis and mitigating chronic illnesses. This study extracted and purified resistant starch (RS) from finger millet starch (FMS) by physical treatments, ultrasonication (P-US-FMS), and annealing (P-A-FMS) to characterize their prebiotic potential. When RS samples were subjected to in vitro digestion, treated samples, especially P-US-FMS, showed higher resistance to enzymatic hydrolysis. RS samples supported the growth of the probiotic strain Lactobacillus rhamnosus MTCC 1423 in the range of 7.59-8.41 log10 CFU/mL. Applying ultrasonication and annealing has improved RS content to 7.2% and 6.5%, respectively. Physical treatments have modified the crystallinity from A-type to B-type. FT-IR data revealed the presence of high-intensity peaks at 990 cm-1 (C-O-C linkage) and 2925-2930 cm-1 (C-H linkage). Thermal properties of resistant starch were enhanced due to the remodeling of starch granules during retrogradation. The most desirable qualities, such as water solubility index, swelling power, and water absorption capacity, were high in the ultrasonicated sample. These findings underscore the potentiality of finger millet-resistant starch as a prebiotic, offering insights for developing functional foods to prevent gastrointestinal diseases.