Thermal and storage properties of milk fat globules treated with different homogenisation pressures

Abstract

Homogenisation pressure is an important parameter affecting the morphology and thermodynamics of milk. Pasteurised milk (65 °C for 30 min) homogenised at different pressures (20, 30 or 40 MPa) was stored at 4 °C for one week, and milk fat globules (MFG) were isolated from it every 24 h. Results showed that homogenisation destroyed milk fat globule membrane (MFGM) and reduced significantly (p < 0.05) the size of MFG. When homogenisation pressure was >30 MPa, the size of MFG did not increase significantly (p > 0.05) during storage. Homogenised milk induced the formation of a new MFGM by adsorbing casein and whey protein on MFG surface, and homogenisation clusters were formed by sharing membrane proteins during storage. Crystallisation of homogenised milk formed a new exothermic peak at 20.6 °C. A transformation of α → β' → β polymorphs accompanied by an increase in crystallisation and melting temperatures occurred during storage.