Formation and properties of milk fat crystal networks

Upon crystallization, fats form 3D networks of crystals entrapping oil. It is due to this complex multiscale structure that fats behave as viscoelastic materials. The physical properties of fat crystal networks are critical for several products (e.g. chocolate, butter, cream, spreads, cheese) where fat has an important structural contribution. In milk fat (MF), rheology and crystallization are determinant factors for processing, functionality and characteristics of several dairy products [1]. To achieve efficient process design and engineering of fat structured products, it is critical to understand the crystal network structure along a broad length scale, the mechanisms involved in its formation and the way in which certain factors affect it.

It has been commonly demonstrated that composition together with processing conditions greatly determine fats structure, crystallization and rheological properties [2]. However, as was pointed out already in the late nineties, and remains valid today, there are no conclusive theories that can directly link triglyceride (TAG) composition and crystallization properties to the macroscopic rheology of the network [3].

Aim
This project aims to study the structure, formation kinetics and rheological properties of MF crystal networks. More information in this regard could help to elucidate the mechanisms involved and the role that processing and compositional variations play in fat crystallization. Ultimately, this research will contribute to the efforts to predict and modulate MF crystal networks based on processing conditions and composition.

Approach
The mechanisms involved in the formation of MF crystal networks will be studied by means of different techniques such as XRD, NMR, DSC and rheology. Because MF flow and deformation properties are strongly correlated to crystallization and have an enormous importance in texture and processing of dairy products, special attention will be given to the rheological assessment of the crystal network.

References

1. Wright, A.J. and A.G. Marangoni, Crystallization and Rheological Properties of Milk Fat, in Advanced Dairy Chemistry Volume 2 Lipids, P.F. Fox and P.L.H. McSweeney, Editors. 2006, Springer US: Boston, MA. p. 245-291.

2. Acevedo, N.C. and A.G. Marangoni, Nanostructured fat crystal systems. Annual review of food science and technology, 2015. 6: p. 71-96.

3. Narine, S.S. and A.G. Marangoni, Mechanical and structural model of fractal networks of fat crystals at low deformations. Physical Review E, 1999. 60(6): p. 6991-7000.