Effect of composition and storage conditions on the flowability of dairy powders

This work investigated the influence of composition (moisture, fat, lactose and protein content) and storage conditions (temperature, time and moisture sorption from air) on the flowability of dairy powders. This was undertaken by measuring the flow properties of eight different commercial dairy powders using shear testing techniques and by measuring how temperature and exposure to moisture in air affected their flowability. Differential scanning calorimetry was used to measure phase and state transitions. The dominant compositional factors affecting the cohesiveness of dairy powders were moisture, amorphous lactose and fat content. All powders had a tendency to absorb moisture from air when in intimate contact with air, however the powders with greater amounts of amorphous lactose were more sensitive to absorbing moisture, giving rise to lumping and caking problems. Fat content had a major influence on powder cohesiveness, with greater particle surface fat content resulting in greater cohesiveness.