Impact of lipophilic surfactant on the stabilization of water droplets in sunflower oil

Abstract

The food industries are continuously facing enormous challenges in the formation of stable w/o emulsions. The stability of the w/o emulsions is a key factor when being used as primary emulsions for the formation of double emulsions (DE). Long-term stability of the primary emulsions in a DE is still a non-solved challenge. Therefore, a mixture of various surfactants or the chemical composition of Polyglycerol Polyricinoleate (PGPR) as a surfactant for stabilizing the emulsion is a scientific interest to alleviate this problem. In order to stabilize the water droplets, two lipophilic surfactants, namely PGPR: Sorbitan monolaurate (Span 20) and PGPR: Sorbitan monooleate (Span 80), blends in various ratios, and various total surfactant quantities were used. The properties of the emulsions have been evaluated in terms of structure, droplet size, stability, and viscosity. The influence of three different providers of PGPR with different chemical compositions on the water droplets is also investigated. Results show that the provider of PGPR significantly affects the properties of the emulsions. PGPR from providers A and B results in emulsions with similar droplet sizes (12 and 13 μm, respectively) and stability using the rotor-stator device at 10,000 rpm, whereas PGPR from provider C yields emulsions with the lowest droplet size (1.7 μm). The mass spectrometric analysis shows that the C PGPR contains lower molecular units with fewer impurities. Therefore, the interfacial tension of the C PGPR exhibits significantly lower values compared to the other two, leading to the production of droplets with the lowest size. Furthermore, the emulsion properties are shown to be affected by the type or concentration of the surfactants. Overall, blends of PGPR: Span and the PGPR provider can tailor the physicochemical properties of w/o emulsions. Novelty impact statement The effect of three different providers' PGPR (a lipophilic surfactant) on the emulsion properties and stability. The small molecular weight of PGPR shows a lowering interfacial tension, which provides smaller emulsion droplet size and in consequence higher viscosity and higher stability. Proposed optimum compositions of PGPR-Span 20 or Span 80 blends for obtaining the best stable structure of w/o emulsions.