Molecular structures of gellan gum imaged with atomic force microscopy in relation to the rheological behavior in aqueous systems. 1. Gellan gum with various acyl contents in the presence and absence of potassium

摘要: Abstract Four samples of gellan gum in sodium form, with equivalent average molar mass but different acyl contents, were investigated using atomic force microscopy (AFM) and dynamic viscoelasticity measurements. The investigation was carried out at concentrations which form local molecular assemblies, including associations, networks, gels. AFM showed that continuous network structures developed mainly through end-to-end type inter-helical associations rather than side-by-side ones the presence potassium without significant increase vertical height on image. Although certainly occurred, did not develop absence potassium. In cation, formation could relate to rheological thermal hysteresis between sol-to-gel gel-to-sol transitions storage modulus 20 °C for lower contents. During gelation, groups flexibility bundles, inhibiting backbones when added minimizes electrostatic repulsion. Also, charge density would promote cation or stabilization double helix (especially via glycerate groups). This elasticity gelled system cation. Our results point fibrous model gelation conventional assumes distinct junction zones disordered flexible polymer chains connecting adjacent zones.