Pea Starch Pasting and Retrogradation Properties and their Modulation by the Addition of Natural Compounds: Molecular Insights via 1H-NMR Relaxation

Abstract

Pea starch (PS) has a rapid retrogradation rate, which limits its industrial applications. This study evaluated the effects of adding varying concentrations of xylitol (X), Arabic gum (AG), and pectin (P) on the pasting properties and retrogradation kinetics of PS-based systems using nuclear magnetic resonance (¹H-NMR) and differential scanning calorimetry (DSC). Results showed that the addition of X diminished PS pasting properties due to water uptake, limiting its availability for starch gelatinization. Nevertheless, X was effective in reducing solely the PS short-term retrogradation at 1% addition, while these effects were not significant at higher concentrations or longer storage times, possibly due to a displacement of these small molecules by the large starch chains with natural tendency to reassociate. AG had no significant impact on either the pasting or retrogradation properties and this could be possibly due to the predominance of AG intermolecular interactions that did not alter water availability or starch mobility and reorganization during storage. In contrast, P significantly increased the viscosity of the suspensions by the establishment of multiple non-covalent interactions, limiting PS gelatinization and restricting amylose leaching, that led to delaying its reorganization rate. 1H-NMR provided in a fast, easy, and non-destructive way insights into the mechanisms behind gel formation, the assessment of the retrogradation kinetics and water syneresis by tracking changes in the proton populations during storage. Overall, this study demonstrates that modifying PS associations by adding natural compounds can improve its storage stability, expanding its potential for both food and non-food applications.