Morphological descriptors and colour as a tool to better understand rehydration properties of dairy powders

The influence of particle size and shape on the rehydration properties of dairy powders has been investigated on five different milk powders more or less agglomerated (a total of thirty-five powders were studied). Morphological descriptors (size, sphericity and convexity) were followed by a Qicpic™ laser diffraction analyzer. Concurrently, the wettability, solubility and dispersibility for each powder were measured. A correlation among particle size and rehydration aptitude was highlighted. Principal component analysis of the rehydration data permits to differentiate powders according to their nature (with colour measurements) but also to their size and morphology. Then, by the use of the shape descriptors, prediction models for dispersibility and solubility were successfully developed and optimized whereas reliable wettability predictions remained unattainable. Results suggested that the size associated with the shape descriptors could be important factors influencing milk powders rehydration properties.