Effect of Cooling Rate on Milk Fat Crystallization and Rheology

Effect of Cooling Rate on Milk Fat Crystallization and Rheology 

The fractal dimension of the fat crystal network in milk fat decreased from 2.5 to 2.0 when the cooling rate was increased. Concomitantly, the particle-related constant, A, increases. These results demonstrate how a faster cooling rate leads to a less ordered spatial distribution of mass within the microstructural network, which would result in a lower value of D, and a decrease in the average particle diameter, which would result in a higher value of A, as predicted by our model. These microstructural changes were correlated with a much higher yield force value for the rapidly cooled milk fat (64.1 3.3N versus 33.0 3.9N for the samples cooled at 5.0°C/min and 0.1°C/min, respectively). 

The effect of the minor components was kinetic, rather than thermodynamic. Although the crystallization kinetics were altered, the structure and mechanical properties of milk fat were the same with or without the minor lipids. The samples reached the same SFC value and had a similar microstructure as observed visually and as characterized by the fractal dimension. The rheological properties of the fats were also similar. Neither the storage modulus nor the yield force was affected by removal of the minor components (Wright and Marangoni, 2003). Large changes in the 

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