The perfect hydrocolloid stabilizer: imagination versus reality

We consider the validity of the hypothetical concept of the perfect hydrocolloid stabilizer with particular reference to its functional role in the preparation, storage, eating, and digestion of biopolymer-stabilized oil-in-water food emulsions. From an equilibrium theoretical perspective, it is demonstrated that the optimum macromolecular ingredient is a soluble hydrophilic block copolymer of low net charge containing strongly adsorbing hydrophobic groups located in a single localized region. From a dynamic colloidal perspective, the ideal macromolecular emulsifier/stabilizer is sufficiently flexible to adsorb rapidly at the interface, leading to a thick, coherent interfacial film, which is resilient to catastrophic structural failure. The ideal hydrocolloid is associated with a smooth mouthfeel as a consequence of its relatively high viscosity and its role as a saliva-interacting lubricant in thin films between oral surfaces. It acts pharmacokinetically through its resilience to proteolytic gastric digestion and by the promotion of a diffusive barrier to lipolytic enzymes within the small intestine. From a glycaemic response perspective, it retards gastric emptying by gelling under acidic conditions, and it affects lipid digestion kinetics by binding to lipases and/or chelating bile salts. As dietary fibre, it generates a high viscosity, is highly fermentable, and binds gut-beneficial compounds. Although we accept the implausibility of a single macromolecular species being able to satisfy all these separate requirements in full, we are of the opinion that the most significant of these desirable characteristics are consistent with the generic concept of the perfect stabilizing ingredient as some kind of protein–polysaccharide conjugate, complex, or microgel structure.