DENSITY and COMPRESSIBILITY of SELECTED FOOD POWDERS MIXTURES1

The density and compressibility of various mixtures of granular and powdered sucrose, granular malic acid, soy protein and cornstarch, at 1:3, 1:1 and 3:1 were determined and compared to those of the pure components. Unless the particles were of similar size and properties (e.g., granular sucrose and malic acid) and density and/or compressibility could not be deduced from those of the pure ingredient, as a result of the formation of new bed structures. This was particularly the case in powders exposed to elevated relative humidity conditions, in this work aw= 0.65. Because compressibility can reflect changes in the bed structure as well as deformation of the particles themselves, no correlation could be found between loose bulk density and compressibility. Therefore, each mixture ought to be treated as a new powder the bulk properties of which are determined by their particular microstructure and the water moisture of their components.