Adjusting rheological properties of concentrated microgel suspensions by particle size distribution

For concentrated model suspensions consisting of hard spheres, besides the volume fraction, the particle size distribution affects rheological properties, where the relations have been investigated and mathematically described in detail. In contrast, food products often represent complex multiphase systems what demands the consideration of other parameters, e.g., particle interaction and deformation. The principles have been shown to be appropriable to chocolate, which consists of non-spherical, hard particles suspended in a Newtonian fluid (cocoa butter). However, work for concentrated fermented milk products, e.g., fresh cheese, consisting of soft microgel particles with high serum binding is lacking. Therefore, the aim was to produce and characterize different particle size distributions by modifying the post-processing during fresh cheese production (protein content 8.0%). Tempering of the standard generated mainly fine, medium, and coarse particle fractions, and, likewise, increased rheological properties (storage modulus, shear viscosity) and synaeresis. Subsequent blending adjusted intermediate levels. Additionally, with increasing size ratio of the particle fractions generated by tempering, the rheological properties of the blended microgel suspensions were affected differently, e.g., high particle size but low shear viscosity. Besides the size ratio, that was related to the particle properties and fundamentals of multimodal particle mixtures. (C) 2015 Elsevier Ltd. All rights reserved.