Conformation and hydration property of low-acetyl gellan gum under microwave irradiation: Experiments and molecular dynamics simulations

The effect of microwave irradiation on the conformation and hydration properties of low-acetyl gellan gum was investigated to reveal the mechanism using experimental methods and molecular dynamics (MD) simulations. The experimental data showed that cross-sectional radius of gyration of the gellan chain treated by microwave or water bath were identical and microwave treatment could improve the water holding capability and restrict water mobility. On the other hand, results of root-mean-square deviation (RMSD) and root-mean-square fluc-tuation (RMSF) showed that microwave irradiation had little impact on the structural conformation of the low-acetyl gellan molecule. The analysis of radial distribution function and interaction energy demonstrated that microwaves modified the gellan-water molecules structure by energy transfer, making hydration shells of the gellan molecule become more structured. In addition, there was an enhancement of the average hydrogen bond number and lifetime under microwave irradiation due to rearrangement and reorient of molecules. These findings can explain the mechanism of microwave-promoted gellan gum gelation to some extent, which enhance industrial applications of low-acetyl gellan.