Stabilization mechanisms of O/W emulsions by cellulose nanocrystals and sunflower protein

Abstract

Oil-in-water (O/W) emulsions stabilized by cellulose nanocrystals (CNC) and/or sunflower proteins (SFP) were produced, aiming to study the effects of each and the mixture of these stabilizers on the interfacial behavior and physicochemical properties of O/W emulsions. The presence of CNC (non-surface activity compound) did not affect SFP solutions' adsorption kinetics since there were no differences in the interfacial tension curves of SFP and mixtures of stabilizers over time. However, either stabilizer provided alone high resistance against droplet coalescence over time (no evidence of oiling-off and no difference in the mean droplet size values), even systems with less viscoelastic interface (2 % CNC). Although droplet coalescence was prevented by steric hindrance and reduction of interfacial tension between the oil–water phases provided by CNC and SFP, respectively, these emulsions were unstable to the creaming phenomenon. Only the mixture of these stabilizers was able to prevent both destabilization mechanisms, initially by adsorption and anchoring of SFP on the interface, followed by adsorption of CNC in the free interface spaces, and finally by the interaction of non-adsorbed CNC particles in the continuous phase, which led to an increase in system viscosity. Thus, based on the results of interfacial properties and emulsions characteristics, we had a better understanding of stabilization mechanisms of O/W emulsions by a food-grade particle and a plant-derived protein.