Structural and thermal properties of acidic and potassium high acyl gellan

Acidic and potassium high acyl gellans, AcHAG and KHAG, respectively, were prepared from a commercial product (LT-100). The average content of potassium in KHAG (1.01%, dry weight, dw) was 2.24 times higher than in LT-100 and approximately 34 times more than in AcHAG. X-ray powder diffraction and 13C NMR analysis revealed structural differences between AcHAG and KHAG, which have been explained on the basis of the effect of different organization of both forms in the solid-state. The FTIR-ATR spectra of AcHAG showed well defined amide I and amide II bands attributed to amino acid residues. TG-DTG profiles were different for AcHAG and KHAG, suggesting that cations have an important role in gellan structure organization, consequently in its thermal stability and the macroscopic physicochemical properties.

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