Fabrication of stable Pickering emulsion using hybrid particles comprised of biopolymers

Today, Pickering emulsions, as the most stable type of emulsion, have been widely accepted for use in various food, pharmaceutical, and cosmetic products. The common use of biopolymers such as proteins and polysaccharides as stabilizing or thickening agents in the formulation of these emulsion systems, due to their inherent functional characteristics, easy preparation, nutritional value, biodegradability, and biocompatibility, encourages researchers to design new hybrid Pickering stabilizers with enhanced functional properties. Therefore, in the present study, the fabrication of sodium caseinate/soy soluble polysaccharides conjugate nanoparticles and the potential of these novel emulsifiers to stabilize the Pickering emulsion was investigated.

Materials and methods:

First, sodium caseinate/soy soluble polysaccharides conjugates (NaCS/SSPS) with a protein/polysaccharide ratio of 9 to 1 were produced through the Maillard reaction using the dry heating method under optimal conditions (temperature of 60 oC and 75% relative humidity ), and after confirming the formation of covalent binding between NaCS and SSPS via attenuated total reflectance-Fourier transform infrared spectroscopy, the conjugate capability to create a stable emulsion was studied, and compared to native biopolymers. Then, to produce NaCS/SSPS conjugate nanoparticles (Pickering stabilizer), ultrasonic pulse treatment was applied (400 W- 28 minute) and two important features of particle size and their wettability were measured. In the following, the potential of Pickering emulsion formation using NaCS/SSPS conjugate nanoparticles was characterized and the stability of obtained emulsions was compared to that of untreated NaCS/SSPS conjugates.

The formation of covalent binding between NaCS and SSPS and structural changes of NaCS during conjugation reaction were detected through attenuated total reflectance-Fourier transform infrared spectroscopy. Increased physical stability against creaming was observed for emulsions stabilized by conjugates when compared with those produced by the native biopolymers. In addition, differential scanning calorimetry results showed that the thermal stability of NaCS was significantly increased by glycosylation reaction. Based on the dynamic light scattering and contact angle measurements, the ultrasonic treatment led to a significantly decreased particle size and an increase in their wettability, which allowed the creation of a high stable Pickering emulsion. The enhanced wettability of the NaCS/SSPS nanoparticles was achieved by exposing the hydrophobic sections hidden within the conjugate structure.

Owing to the successful fabrication of high stable Pickering emulsion using the hybrid nanoparticles produced by combining two techniques of conjugation and ultrasonic method, it can be suggested to employ NaCS/SSPS conjugate nanoparticles for the manufacture of Pickering emulsion delivery systems for bioactive compounds.