Soluble protein particles produced directly from mung bean flour by simple coacervation

Poor solubility is a common characteristic of many plant protein ingredients which often hampers product formulation. We exploit simple coacervation, or liquid-liquid phase separation, of plant proteins in flours, to formulate plant proteins as powders consisting of submicron colloids with good solubility and dispersibility. We consider the specific case of mung bean flour, but the approach is more general. First, we study the influence of pH on the formation of submicron protein droplets ("coacervates") after alkaline protein extraction from mung bean flour. Next, the proteins in droplets were heat-set into colloidal protein microgels, and the morphology of the colloids was assessed by scanning electron microscopy. The mung bean protein colloids have an intrinsic viscosity much lower than typical food thickeners, indicating the dense nature of the particles. After spray-drying, they maintain a good dispersibility even close to the isoelectric point. Heat-induced gelation of redispersed protein particles resulted in gels with moduli much less than those of commercial mung bean protein concentrates at equivalent protein concentration. Hence, the main impact of the pretreatment is on dispersibility and heat stability, with relevance to formulations such as plant-protein based beverages.