In vitro starch digestibility and physicochemical properties of chemical and enzymatic modified Indian Teff (Eragrostis Tef) starch for industrial applications.

The long-term stability, mechanical properties, and interactions of modified teff starch with food components remain unclear. The effects of dual or multiple modifications on physicochemical properties and digestibility are also unexplored. This study investigates the modification of Teff starch through oxidation (sodium hypochlorite), cross-linking (citric acid), and enzymatic treatments (α-amylase, amyloglucosidase) to enhance its structural, physicochemical, and thermal properties. Oxidation reduced swelling power and pasting viscosity, while cross-linking improved mechanical resistance with a cross-linking degree of 44.2 %-70.4 %. Enzymatic modification lowered amylose content and enhanced gelation. In vitro digestibility analysis revealed increased slowly digestible starch (SDS) and resistant starch (RS) contents for all modified starches. O2 showed SDS and RS levels of 44.64 % and 31.42 %, respectively, compared to 41.51 % and 21.28 % in NS. C2 demonstrated RS levels of 24.11 %, while AA exhibited an RS of 29.03 %. O1, O2, C1 and C2 reduced starch digestibility by introducing steric hindrance and cross-linking bridges, while AA increased branching density, slowing digestion. Structural analyses (FTIR, DSC, XRD, SEM, and H NMR) confirmed functional group stabilization, enhanced thermal stability, partial amorphization, and surface integrity improvements. The X-ray diffractograms showed no notable alterations, confirming that the crystalline region remained unaffected by the reaction. H NMR spectra revealed changes in glycosidic linkages, with oxidation reducing branching and cross-linking increasing structural complexity. PCA revealed the distinct properties of modified starches. The study highlights the synergistic effects of oxidation and cross-linking, offering insights into starch modification mechanisms and future industrial applications.