Isothermal crystallization behaviour of milk fat in bulk and emulsified state

Isothermal crystallization behaviour of natural and recombined creams and their bulk milk fats was examined at 5 °C using differential scanning calorimetry to analyze crystallization kinetics, X-ray diffraction to elucidate the crystallization mechanism and nuclear magnetic resonance to measure solid fat content during storage. Milk fat in bulk and in cream showed the same crystallization mechanism if rapidly cooled (25 °C min−1) to 5 °C. First, α-crystals were formed and second, β′-crystals grew at the expense of the α-crystals. Some α-crystals still persisted and additional crystallization during further cooled storage took place. The observed mechanism is explained by means of the formation of compound crystals. Overall crystallization was delayed in both natural and recombined cream. Moreover, the crystallization behaviour of natural cream deviated from that of recombined cream, which is mainly explained by the variation in triacylglycerol composition of the individual globules in natural cream.