Effect of diutan microbial polysaccharide on the stability and rheological properties of O/W nanoemulsions formed with a blend of Span20-Tween20

ABSTRACT

The stability and rheological behavior of oil-in-water (O/W) nano-emulsions formed with a blend of Span20-Tween20 have been studied with and without diutan microbial polysaccharide. It is found that there exist thresholds for the water content and emulsifier to obtain stable nano-emulsions using the emulsion inversion phase (EIP) method. The viscosity of the nano-emulsion is proportional to the emulsifier content and inversely proportional to the water content. High emulsifier content is not conducive to the thermal stability of the nano-emulsion. The addition of diutan gum with negative charge into the nano-emulsions increases the electrostatic repulsion between droplets and makes the droplet size smaller and more unifom, slowing down the coalescence and Ostwald ripening of the nano-emulsions. Due to the association of the diutan gum double helix, a three-dimensional network structure is formed in the continuous phase of nano-emulsions, which improves the stability of nano-emulsions and is also the main factor giving the nano-emulsion high viscoelasticity at high temperature. This study offers new insight into the nano-emulsion containing microbial polysaccharide and may serve as a guideline for practical applications of new nano-emulsion systems.

GRAPHICAL ABSTRACT

KEYWORDS:

• Diutan gum
• nano-emulsion
• rheology
• stability
• viscoelasticity

Additional information

Funding

We gratefully acknowledge financial supports from the China Postdoctoral Science Foundation (Grant No. 2017M612377), the Natural Science Foundation of Shandong Province, China (Grant No. ZR2017BEE064), the Introduced Talent Research Foundation of China University of Petroleum (East China) (Grant No. YJ201601098), and the Fundamental Research Funds for the Central Universities (Grant No. 17CX05005, 18CX02165A).