Basic concepts of bulk rheology in food emulsions

Many food products are thermodynamically unstable emulsions (butter, margarine, mayonnaise, etc.), which can reach a kinetic stability through a convenient formulation and processing. There is a clear codependence between the stability of a food emulsion and its rheology, mainly dictated by the microstructure (i.e. the droplet size distribution). Thus, a comprehensive rheological characterization is of great help when optimizing the industrial production of emulsion systems. In Chapter 2, our colleagues have presented an introduction to food properties and techniques in food product development. In this chapter, we will focus our discussion specifically on liquid foods, particularly food emulsions. It is the objective of this chapter to describe the basics of food emulsions, to present the main emulsification processes, and to delineate the rheology of the continuous phase and of the final emulsion. Main rheological tests and parameters are described, stating their utility when looking to avoid the common destabilization mechanisms.