Multiple phase transitions and microstructural rearrangements shape milk fat crystal networks

Area of Science:

• Food science and technology
• Materials science
• Physical chemistry

Background:

• The rheology of milk fat is crucial for its functionality.
• Milk fat functionality is influenced by the colloidal network formed by crystallizing triacylglycerols.
• Understanding the multiscale structural transitions within this network is key.

Purpose of the Study:

• To correlate the rheological properties of milk fat with its structural changes during early crystallization stages.
• To investigate the formation of different triacylglycerol polymorphs and their impact on rheology.
• To establish a method for early detection and quantification of milk fat structural transitions.

Main Methods:

• Studied milk fat crystallization at 15-22 °C.
• Employed X-ray diffraction (XRD) and microscopy for structural analysis.
• Utilized Nuclear Magnetic Resonance (NMR) for structure quantification and rheology for macroscopic property evaluation.

Main Results:

• Network strength increased with synchronized micro- and nanostructure formation.
• Rheological response was observed upon microscale structural connection and internal transitional changes.
• Nanoscale transitions correlated with specific crystal polymorph formation, including less common ones (β-2, β2'-2).

Conclusions:

• The study quantifies polymorph formation in milk fat and relates it to fat composition.
• Combines XRD, NMR, rheology, and microscopy for comprehensive characterization of milk fat structural transitions.
• Demonstrates early detection of structural changes in milk fat crystallization is feasible.