Isolation, physicochemical characterization, fractionation, and in vitro digestibility of non-conventional starches from Pueraria montana var. thomsonii and Eleocharis tuberosa

• Isolation of non-conventional starches from Kudzu and Chinese water chestnut. • PMS and ETS showed significantly different viscoelastic properties. • PMS exhibited comparatively lower digestibility related to higher RS contents. • FT-IR spectra showed that all starches possess their carbohydrate nature. • The commercially available starches (CS and PS) could be replaced with PMS and ETS. The primary objective of the present study was to introduce novel starch sources from underutilized and non-conventional sources, namely Pueraria montana var. thomsonii and Eleocharis tuberosa, which are named PMS and ETS, respectively. The starches were characterized for their chemical composition, particle size, swelling power, solubility, morphological features, pasting and viscoelastic properties, and mechanism of in vitro digestion. The FTIR spectra peaks showed the polysaccharide nature of isolated starches. PMS showed high swelling power and solubility compared to ETS, PS (potato starch), and CS (corn starch). In vitro digestion showed a higher resistant starch (RS) content (50.29%) in PMS, leading to a higher tendency for physical crosslinking through retrogradation and exhibiting the highest G′ and setback viscosity (1724.00±3.50 a ) ratio with subsequent cooling-induced gelation succeeding gelatinization. This study will aid future research into these non-conventional isolated (PMS, ETS) starches and their prospective applications in food and non-food industrial products.