Direct measurement of thermal fat crystal properties for milk-fat fractionation

The temperature dependency of the solid-fat content of a fat is important for predicting the consistency of the final product and for process control. Two direct analytical methods for determining the solid-fat content and the melting characteristics of milk-fat fractions have been developed. The fractions are analyzed during crystallization, and the results give reproducible information about the thermal behavior of the fractions and the actual crystal amount in the suspensions. The results are obtained within minutes, and no separation of the fractions before the measurement is necessary. New ways of reducing process time are proposed. It is possible to adapt crystallization time to seasonal variations of the initial milk fat and to the required properties of the final product. Partially crystallized milk fat was directly measured in a calorimeter and a pulsed nuclear magnetic resonance spectrometer. The data showed good correlations and even more accurate results than the conventional methods. The calorimetric method makes it possible to detect polymorphic changes and co-crystallization in the crystals so that the influence of processing parameters, such as energy input, on crystallization behavior can be investigated.