Changes in the functional properties of milk protein powders: the impact of concentration and drying

Vacuum concentration and spray-drying are water-removal techniques used to biologically stabilise the majority of dairy ingredients. Advances in membrane technologies have enabled the diversification of these ingredients in terms of composition, creating a need to better understand the effects of membrane concentration, vacuum concentration and spray drying on the quality of the powders. Numerous publications have demonstrated the role of proteins in water transfer during drying and rehydration. The residence time of droplets and powder in a drying tower is so short that it is very difficult to study changes in protein structures without examining process-product interactions. However, several studies have shown that the main changes occur prior to drying, during the concentration and heat treatment stages. Thus, following an introduction to milk powders, this article will first explain the major processes used in the manufacture of powdered dairy protein ingredients, then go on to detail the various properties and qualities of these powders, before concluding with a discussion of the biochemical and physicochemical changes induced during the manufacturing process.