Rheology and Texture of Cream, Milk Fat, Butter and Dairy Fat Spreads

Abstract

‘Rheology’ is a branch of physics concerned with deformation and flow experienced by complex fluids and soft materials such as foods when acted on by forces. Such forces may be ‘naturally’ exerted (e.g. gravitational or interaction forces holding a structure) or deliberately applied during their industrial process, use or consumption. Without exception, rheological phenomena occur in cream, milk fat, butter and dairy blends where it plays essential roles in fundamental, technological and sensorial aspects. Specifically, rheological properties provide information about interaction forces and reversible/irreversible flow of the structural elements of the mesoscopic network. It also relates to the application, “in-use” textural and sensorial properties (e.g. incorrect blending of milk fat fractions leads to macroscopic softening attributed to eutectic formation). Furthermore, it contributes to understanding the effects of formulation and processing. This information is used to establish rheology-structure relationship (e.g. develop models linking shear modulus and microstructure), rheology-texture relationships (e.g. describe firmness in terms of shear compliance), and rheology-formulation-processing relationships (e.g. assess the effect of cooling on firmness), all equally important to understand, control and improve product quality and process performance.