New Food Hydrocolloids Paper on Pea protein microgel-stabilized emulsions

Research published in Food Hydrocolloids by Shuning Zhang (PhD student) demonstrates a new class of plant protein particles i.e. pea protein microgels created using a facile top down approach to stabilize oil-in-water (O/W) Pickering emulsions with ultrastability against coalescence using a combination of experimental approaches and theoretical considerations. Aqueous dispersions of pea protein microgels showed highest degree of particle aggregation at pH 5.0 as the activation energy barrier in particle-particle interaction potential was calculated to be extremely low at this pH. Meanwhile, high salt concentrations resulted in charge screening effects in PPM dispersion but the resulting reduction in electrostatic potential did not affect the hydrodynamic diameter of microgels, suggesting that other, possibly steric effects might also be playing a role in the colloidal stability of these particles. Interestingly, when the pea protein microgels were present at the oil-water interface, ultra-stable emulsion droplets were obtained only at microgels with 1.0 wt% protein concentration with all protein subunits i.e. legumin, vicillins and convicillins, being simultaneously present on the microgel-laden interface. The packed layer of PPM particles stabilizing the oil droplets allowed the emulsions to be stable over few months against coalescence. Upon pH reduction to pH 5.0, both intra-droplet and inter-droplet aggregation of PPM occurred resulting in higher adsorption efficiency and higher viscosity, respectively.  To our knowledge, this is the first comprehensive study that has systematically demonstrated the role of electrostatics in the colloidal stability of the plant-based microgel particles in bulk phase versus particles adsorbed at the surface of the droplets. Findings from this comprehensive study might open door for applicability of these pea protein-based microgels in a range of food products and allied soft-matter applications, where alternative plant-based sustainable Pickering stabilizers are increasingly necessary. To read the paper in Food Hydrocolloids (2020), Volume 102, Article no. 105583, click here https://doi.org/10.1016/j.foodhyd.2019.105583