Use of a turbidity sensor to determine dairy powder rehydration properties

A method using a turbidity sensor has been developed to study rehydration of dairy powders. The process involved dispersing powder in a stirred vessel equipped with a turbidity sensor under standardized conditions. The changes of turbidity occurring during powder rehydration highlighted several stages including particles wetting, then swelling as the water penetrates into the powder bed, followed by a slow dispersion of the particles. The following information was obtained: wetting time (Tw), swelling time (Ts) and rehydration time (Tr). The results are in agreement with static light scattering and optic microscopy analyses. Finally, the method was used for the characterization of two powders (native phosphocaseinate and whey proteins isolate) differing in their rehydration properties.

Most of these solid products are produced as easy to process, free flowing powders or granules. If these products cake, they loose most of their value. In this paper work concentrates on caking due to crystal bridges formed under the influence of humidity. It is shown how to predict the bulk strength of caked solids from individual particle contacts measurements performed in a new test device. Modelling was done using contact-dynamics model adapted to caked systems and employing the complete crystal bridge strength distribution in the simulation.Figure optionsDownload as PowerPoint slide