Conformational transition of native and modified gellan

Area of Science:

• Biopolymer characterization
• Food science and technology
• Materials science

Background:

• Gellan is a microbial polysaccharide forming gels with unique properties.
• Understanding gellan's conformational transitions is crucial for its applications.
• Native and deacylated gellan exhibit different structural and rheological behaviors.

Purpose of the Study:

• To characterize native gellan using differential scanning calorimetry (DSC) and rheology.
• To investigate the influence of external salt concentration on gellan's stability and gel properties.
• To compare the behavior of native gellan with deacylated gellan.

Main Methods:

• Differential Scanning Calorimetry (DSC) to determine transition temperatures (Tm) and enthalpy.
• Rheological measurements (G' and G'') to assess gel strength and viscoelasticity.
• Systematic variation of external salt (NaCl) concentration.

Main Results:

• Native gellan exhibits a loose gel state (G' > G'') at ambient temperature, which diminishes above 60°C.
• Salt concentration has a minor effect on the Tm of native gellan.
• Deacylated gellan shows greater sensitivity to salt concentration, with increased gel strength and hysteresis in conformational transitions.

Conclusions:

• Native gellan's helical structure is relatively stable across varying salt concentrations.
• Deacylated gellan's gelation is significantly enhanced by increased salt, leading to a more robust gel network.
• Conformational changes in gellan directly correlate with its observed rheological properties.