Thermal and Structural Behavior of Milk Fat

Area of Science:

• Food Science
• Materials Science
• Crystallography

Background:

• Milk fat globules in cream contain triacylglycerols (TGs) that exhibit complex crystallization behaviors.
• Understanding the thermal and structural properties of these TGs is crucial for dairy product processing and stability.

Purpose of the Study:

• To investigate the thermal and structural properties of unstable triacylglycerols (TGs) crystallizing in milk fat globules.
• To characterize the polymorphic behavior and crystallization kinetics of TGs in cream emulsions.

Main Methods:

• Simultaneous time-resolved synchrotron X-ray diffraction (XRDT) at wide and small angles and differential scanning calorimetry (DSC) were employed.
• Experiments were conducted over a temperature range of -8 to +50 degrees C.

Main Results:

• Small-angle X-ray diffraction revealed two lamellar phases (2L and 3L) for the unstable alpha form of TGs formed upon cream quenching.
• The bilayered TG structure proved highly unstable, disappearing within 20 minutes at -8 degrees C.
• Heating experiments demonstrated the monotropic polymorphism of cream TGs.

Conclusions:

• Crystallization in cream emulsion droplets is similar to bulk anhydrous milk fat but exhibits increased disorder.
• Interface curvature in emulsion droplets is attributed as the cause for the observed disorder in TG crystallization.