Rheological and structural characterization of succinoglycan obtained by bioconversion of the agroindustrial residue deproteinized whey

Abstract

Succinoglycan is a bacterial exopolysaccharide with thickening, gelling, stabilizing and emulsifying properties. In this study succinoglycan was produced from whey and its rheological and structural characteristics were elucidated. Four culture media were prepared with different ions for bioconversion of whey into succinoglycan. The formulation composed of deproteinized whey, monobasic potassium phosphate and magnesium sulfate allowed the production of 13.7 ± 0.43 g/L of succinoglycan. The rheological results showed that the apparent viscosity of the succinoglycan solutions was directly proportional to the concentration, and the solution showed pseudoplastic behavior. Dynamic frequency sweep tests identified that a concentration of 2.0% of succinoglycan is required for formation of the gel system. Temperature influenced the viscoelastic behavior of succinoglycan and revealed the melting point and reversibility of the gel. The apparent molar mass of succinoglycan was estimated to be 9.033 × 105 g/mol and the polydispersity index was 1.044, representing the homogeneity of the sample. The monosaccharide composition of glucose and galactose for the succinoglycan produced was 6.6:1.0. The 1H RMN analysis revealed the non-saccharide substituent content of 1.2%, 3.0% and 8.1% for acetyl, succinate and pyruvate, respectively. Whey was shown to be a promising carbon source for the production of succinoglycan with thickening potential and viscosity modifier.