Crystal structure, fats

Emulsifiers assist the stabilizing hydrocolloids in controlling crystal structure. They accentuate the function of the homogenizer in reducing the size of the fat globules. They also reduce the interfacial tension between the fat and water phases of the mix. The result is smaller ice particles and air cells when the mix is frozen and a smoother and creamier finished product. 

Element (allotrope) Temperature range/°C Pressure/GPa Crystal structure Lattice parameters/pm Atomic volume, Fat/106pm3 Molar volume/ cmVmol Density/ g/cm3... 

In many instances, TGs exist in polymorphic forms. Crystal structure is very important to the properties of margarines, shortenings, and specialty fats. The very unstable a form is readily transformed to the more stable ft form, which in some TGs has a higher melting point (more stable) than the /3 form. In single-acid TGs, the order is a — f3 — a, but some mixed TGs show a lower-melting (less stable) (3 form. This is further complicated by the existence of multiple / and /3 forms, depending upon the detailed TG structures at hand. 

Some Case Studies. Milk Fat Crystallization Structure and Rheological Properties... 

The crystallization behavior of milk fat is complex, owing, in large part, to its complicated composition. By manipulating composition and crystallization conditions, milk fat and dairy products with unique structures and mechanical properties can be designed. Understanding the relationships between composition, crystallization, structure, rheology and texture is a powerful tool in this regard. 

Precht, D. 1988. Fat crystal structure in cream and butter. In Crystallization and Polymorphism of Fats and Fatty Acids (N. Garti, K. Sato, eds.), pp. 305-361, Marcel Dekker Inc., New York. 

Marangoni s group has since advanced the fractal theory applying Shih et al. s weak link regime with Vreeker s rheological findings to develop a fractal theory for fat crystal networks. Fat crystal networks are considered as cross-linked fractal clusters formed by aggregating fat crystals. Self-similarity is assumed to exist within the clusters, from the primary fat crystals to the clusters. If the force-constant of the links between micro structures was expressed as k/, then the macroscopic elastic constant K (in one dimension) of the network could be modeled as ... 

Hemqvist, J.W. (1988). Crystal structures of fats and fatty acids. In N. Garti K. Sato (Eds.), Crystallization and polymorphism offats fatty acids. Marcel Dekker, pp. 97-138. 

The physical state of fats and oils and their crystal structures are important for application of such products. In addition, formulation of products for special applications such as bakery, confectionary, frying, salad dressing, margarines, and spreads requires special characteristics that make the products suitable for such purposes. Thus, each source material will be important for its physical and chemical characteristics and hence suitability as a food component. 

The three common polymorphic forms that exist in fat crystal networks are the suba, a, (), and (3 modifications. These polymorphic modifications and their characteristic crystallization patterns are shown in Figure 6. The subot and ot forms are metastable (34). Each polymorphic form yields different crystal structures dependent on the magnitude of the crystallization driving force. The polymorphic modifications also have varying thermodynamic stability, which determines their lifetime within a crystal matrix, with the tendency toward greater stability in the order a to (3 to (3 (24, 34). 

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