Development of emulsions using microgels of soy protein isolate and microcrystalline cellulose combinations as stabilizers

Abstract

The development and implementation of technological innovations over the years have made it possible to supply consumers with various processed and industrialized food products on a large scale. Many foods in our daily lives are made of oil and water, for example mayonnaise, salad dressings, and margarine. Therefore, there is a need for the implementation of technologies in order to ensure quality goods for the population, and emulsification is an option often used. Emulsions are thermodynamically unstable systems and their formation is non-spontaneous, so they require incorporation of mechanical energy through agitation and addition of surfactants that decrease the interfacial tension between the fluids, delaying phase separation. Pickering emulsions are an alternative to stabilization by conventional surfactants because they use solid particles to stabilize the systems, which enables to retard destabilization due to creation of a physical barrier strongly adsorbed to the interface between the dispersed droplets and the continuous phase in the emulsions. In this context, the present work aims to produce and characterize Pickering oil-in-water emulsions, composed of canola oil and stabilized by combinations of soy protein isolate (SPI) microgels and microcrystalline cellulose (MCC). Initially, aqueous suspensions with SPI will be heated at 40°C for protein hydration, followed by mechanical homogenization, heating at 90°C (denaturation temperature of protein fractions) and cooling for 12 hours, aiming the formation of a SPI macrogel. In parallel, suspensions with MCC will be prepared by magnetic stirring and left to hydrate at room temperature for 12 hours. Subsequently, the suspensions with MCC will be incorporated to the suspensions with SPI, being submitted to sonication in a power ultrasound, resulting in suspensions containing SPI microgels and cellulose microcrystals. Emulsions will be produced by dispersing different proportions of canola oil in the suspensions of SPI microgels and MCC, followed by a combination of mechanical stirring by ultra-turrax and sonication. The suspensions containing SPI microgels and MCC will be characterized regarding their zeta potential and particle size, whereas the emulsions will be characterized regarding their rheological behavior, kinetic stability, zeta potential, morphology by microscopic analysis, and droplet size distribution. As a control treatment, emulsions prepared with SPI and MCC microgels alone will be evaluated. It is expected to obtain kinetically stable emulsions with microstructural characteristics that allow their application in food systems, in addition to investigating the effects of the combination of two types of micro particulate materials in the stabilization of Pickering emulsions.