Influence of deep-eutectic and organic solvents on the recovery, molecular mass, and functional properties of dextran: Application using dextran film.

The novelty of this study is to examine the impact of different solvent systems, namely organic and deep eutectic solvents, on recovery yield, antioxidant activity, poly-dispersity index, and functional properties of microbial dextran. The optimized conditions for maximum dextran recovery were obtained using organic solvent found to be: supernatant: organic solvent - 1:4 v/v; organic solvents: ethanol, isopropanol, and acetone; temperature: 0 °C; and time: 16 h. Though a similar structure was obtained for dextran recovered using various solvents, the degree of branching varied, with DES-precipitated dextran having the highest branching of 20 % α-(1,3) linkages. Similarly, the molecular mass and functional properties of dextran were significantly influenced by solvents, enabling their different applications. Ethanol-recovered dextran had the highest water-holding capacity (441.7 ± 2.5 %), whose films could be used in agriculture to retain soil water. On the contrary, acetone-precipitated dextran had a maximum solubility (96.0 ± 0.4 %) and antioxidant activity, which could be used as food additives and/or wound dressings. The DES-recovered dextran exhibited high fat-binding capacity (287.1 ± 2.0 %) and emulsifying activity (50.0 ± 2.9 %), making it suitable as an emulsifier in mayonnaise, etc. The isopropanol-recovered dextran showed the highest mass-average molecular mass (3224.8 kDa) and could be employed as flocculants for waste-water remediation.