Abstract
The role of hot water-soluble amylose (WSA) in modulating the mechanical and structural properties of swollen granule-filled starch gels was investigated. Initially, WSA was extracted from potato starch, which was then incorporated into gelatinized waxy maize starch (WMS) systems containing swollen starch granules at concentrations of 0, 8.3%, 16.7%, 25.0%, and 33.3% (w/w). Rheological analysis revealed that, at an angular frequency of 1 rad/s, the storage modulus (G′) and loss modulus (G″) of WMS–33.3%WSA composite gels increased by 14.7-fold and 4.6-fold, respectively, compared to the WMS gel. Texture profile analysis showed a concentration-dependent enhancement in hardness and springiness, with maximum values reaching 492 g and 0.92, respectively. Differential scanning calorimetry and X-ray diffraction analyses showed that the addition of WSA increased the relative crystallinity of the gels from around 4.2% to 21.0%, and the retrogradation enthalpy increased from 3.54 J/g to 5.79 J/g. Small-angle X-ray scattering showed that higher WSA levels promoted the formation of thicker semi-crystalline lamellae and denser gel networks, with the size of the ordered aggregates increasing from around 19.1 to 28.4 nm. This study elucidates the mechanism by which leached amylose and swollen starch granules contribute to the formation of a dense and continuous gel network. During cooling, dissolved WSA molecules rapidly self-assembled into a three-dimensional network structure. Increasing the WSA concentration enhanced the molecular crowding and spatial confinement, which facilitated amylopectin recrystallization within the swollen granules and improved gel strength. Additionally, hydrogen bonding between soluble amylose and amylopectin promoted intergranular bridging, further reinforcing the gel network.
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•Impact of hot water-soluble amylose (WSA) on WMS swollen granule gels was explored.•Higher WSA levels enhanced springiness, hardness, and moduli of granule-filled gels.•Crystallinity of retrograded gels increased (4.2% → 21%) with rising WSA.•High WSA led to denser networks with larger ordered domains (19.1 → 28.4 nm).