Design and fabrication of Sodium caseinate-Tannic acid nanoparticles with polysaccharide coating and evaluation its ability to formation Pickering emulsion.

Abstract

Abstract Background: Nowadays, the use of natural systems to produce beneficial food formulations to protect more sensitive and bioactive compounds on the one hand, and not to use synthetic emulsifiers such as surfactants on the other hand, has received much attention. Tannic acid is considered due to its anti-microbial, antioxidant, anti-allergic, anti-diabetic, anti-cancer and anti-inflammatory activities. In this research, it is intended that casein be modified and used as a fat substitute by forming a complex with tannic acid/glucose and adding antisolvent containing polysaccharide coating to stabilize emulsions with high oil percentage. Materials and Methods: Sodium caseinate colloidal nanoparticles were prepared using the complex and anti-solvent method. At first, 1% w/v sodium caseinate solution was prepared. In the second step, heat treatment at 90 degrees for 1 hour was performed in the presence and absence of glucose (0.4% by weight) and tannic acid in different concentrations (0.05 to 1% by weight). Then, the antisolvent phase containing ethanol and ethyl cellulose dissolved in ethanol (0.5,0.75,1 and 1.5% by weight) was used as the antisolvent phase in different volume ratios (5:5, 5:3). After selecting stable colloidal suspensions, size, interfacial tension, zeta potential, contact angle, and spectroscopic tests were performed to determine interactions and physicochemical properties of modified casein. Finally, a 50:50 water-oil phase emulsion was prepared and the physical and oxidative stability of the resulting emulsion was checked. Results: It was observed that pure sodium caseinate cannot stabilize water and oil phase in 50:50 mixing ratio. Colloidal suspensions prepared from heat-treated sodium caseinate/ethanol antisolvent, heat-treated sodium caseinate glucose/ethanol antisolvent, heat-treated sodium caseinate-glucose-tannic acid/ethylcellulose antisolvent in ethanol have great potential to stabilize picker emulsions. and caused long-term physical stability (2 months and more). Simultaneous modification of sodium caseinate particles using heat treatment and addition of antisolvent (ethanol and ethyl cellulose in ethanol) was necessary to significantly change the behavior of sodium caseinate particles. Based on the FTIR results, the structural composition of sodium caseinate changed due to the formation of a complex and crosslinking of sodium caseinate with glucose and tannic acid after heating and adding antisolvent. Confocal laser scanning microscope images of the emulsions confirmed that the prepared emulsion is a Pickering type of oil-in-water emulsion. The high physical stability of the emulsion in the mixing ratio of oil and water 50:50, shows that the formed solid particles are placed at the interface of oil and water with a suitable contact angle. Conclusion: The prepared emulsions had high physical and oxidative stability, which indicates their high potential in designing food formulations with reduced fat and/or encapsulation systems for use in food and pharmaceutical industries. Keywords: sodium caseinate, tannic acid, ethyl cellulose, antisolvent, Pickering emulsion