Effects of hydrogen bonding and electrostatic interactions on the formation of rice starch-Mesona chinensis polysaccharide gels

Abstract

Non-covalent forces are essential for the formation of starch-Mesona chinensis polysaccharide (MCP) gels. In this paper, the effects of hydrogen bonding and electrostatic interactions on the formation of rice starch (RS)-MCP gels. The addition of urea broke the hydrogen bonds and loosened the microstructure, reducing the gel viscosity, pasting temperature, and water molecule binding capacity. The decreased short-range ordering and double-helix structure corroborated the reduction of gel properties. Gaussian fitting showed that the intermolecular hydrogen bonding between RS and MCP was dominated by OH⋯π. Low concentrations of NaCl decreased the electrostatic repulsion between RS and MCP and promoted the formation of gel structure. The electrostatic shielding effect occurred with increasing NaCl concentration, and the storage modulus (G′) and melting enthalpy decreased. Compared to the changes in the electrostatic effect, the breaking of hydrogen bonds disrupted the gel structures obviously, therefore, hydrogen bonds were the main interaction force in gel formation. The research explored the effect on gel properties based on the changes in non-covalent force, which provided a new insight into starch-polysaccharide interactions. Concurrently, it also presented a novel entry point for research efforts to modulate the properties of gels.