Insights on the molecular interactions of tapioca starch with xylitol, Arabic gum, and pectin and their effects on its pasting properties and retrogradation kinetics

Abstract

Pasting properties and retrogradation kinetics of tapioca starch (TS) systems with different added concentrations of xylitol (X), Arabic gum (AG), and pectin (P) were evaluated by nuclear magnetic resonance (1H-NMR) and differential scanning calorimetry (DSC) after storage at 4 °C for 21 days. The incorporation of the additives reduced the peak, final and setback viscosity of the pastes, indicating limiting gelatinization of TS for the establishment of non-covalent interactions with water and/or starch, restricting further hydration and swelling. Based on 1H-NMR results, free water molecules were involved in the reassociation of amylose and amylopectin chains; thus, their molecular mobility decreased with the progress of starch retrogradation, as evidenced by the diminishment of the spin-spin relaxation times. DSC results confirmed that the addition of X delayed TS retrogradation, possibly due to the generation of hydrogen bonds interactions, while opposite results were obtained when AG was added, which promoted TS molecules reorganization. P showed a concentration-related effect, since it delayed TS retrogradation at 1 % level and accelerated it at 2 % concentration. Results from this study provide insights on the molecular interactions of TS with xylitol, Arabic gum, and pectin and their modulating effects on starch retrogradation, which are valuable for the development of gluten-free products with varied industrial applications.