Physical Properties of Fats and Oils

Understanding the physical properties of lipids is critical to the formulation and manipulation of fats, oils, and fat-structured food products. Rheological properties, and ultimately texture, are closely related to the structures of underlying fat crystal networks (FCNs) in foods. Figure 6.1 shows the hierarchy of parameters that determine the physical properties of lipids and lipid-based materials. Composition and processing parameters determine the crystalline structure and rheological properties of FCNs. Differences at the nano-and microstructural levels in fats translate into differences in terms of functionality and sensory properties. Other networks, including protein, polysaccharide, and ice, may also be present in foods. Each network and the interactions between ingredients all contribute to the overall sensory impressions of foods. This chapter will review the physical properties of lipids, including melting, crystallization, phase behavior, polymorphism, microstructure, and rheology, and the ways in which the physical properties of fats can be modified.