Esterification plays a significant role on apple pectin interaction with wheat starch: Impacting on gelatinization and gels properties

Abstract

Although wheat starch (WS) is widely used in both food and industrial applications, it has inherent limitations such as low gelatinization temperature and viscosity. This study examines the effects of apple pectin (AP) with varying degrees of esterification (24%–57%) on the physicochemical properties and molecular interactions of WS. The impact of esterification on the gelatinization, rheological, and thermal properties of WS was assessed. The results showed that the gelatinization temperature and viscosity of WS were significantly increased by higher-ester AP. The WS-AP composite gels exhibited pseudoplastic behavior, and the viscoelasticity of the composite gels formed by higher-ester AP was enhanced. Higher-ester AP notably reduced the enthalpy (ΔH), swelling power, and transmittance. Higher-ester AP led to a more continuous and regular network structure of composite gels. FT-IR and molecular dynamics simulations confirmed that WS and AP primarily interact through hydrogen bonds, with higher degrees of esterification enhancing hydrogen bond formation. Higher-ester AP facilitated the creation of a denser hydrogen bond network, resulting in a more compact and stable structure in the gel system. This study provides new insights into the application of AP with different degrees of esterification in starch, aiming to improve the physicochemical properties of starch for more effective processing and enhanced functional characteristics.