Formation of β Polymorphs in Milk Fats with Large Differences in Triacylglycerol Profiles

Summary

In this study, we characterized the polymorphism of milk fat (MF) with various TAG compositions during isothermal crystallization at 20 °C. TAG composition of MF from seven individual cows was determined using GC-FID and MALDI-TOF MS, and MF polymorphism was studied using X-ray diffraction. Results showed that TAG profile determines the polymorphic behavior of MF. Saturated TAG with carbon numbers 34-38 promoted the formation of α polymorphs, whereas unsaturated TAG with 52-54 promoted the formation of the β polymorphs. Furthermore, MFs with unsaturated fatty acid profiles were increased in unsaturated TAG with 52-54 carbons. The presence of MF crystals in the β polymorph has been controversial over the years as most authors mainly find MF crystals in the α and β′ form. In our work, we showed that the β polymorph is formed in MF on the basis of its TAG composition.