Influence of droplet clustering on the rheological properties of emulsion-filled gels

• The effect of droplet stiffness and clustering were examined separately.
• Droplet clustering has a relevant effect on the stiffness of emulsion-filled gels.
• Clustering has a larger effect than droplet stiffness.
• The effect of clustering is dependent on the relative stiffness of the droplet.
• Kerner model considering droplet clustering can explain experimental observations.

The aim of this work was to determine the effect and magnitude of fat droplet clustering on the rheological properties of emulsion-filled gels. To this end, we investigated experimentally the effect of fat hardness and emulsion droplet clustering in gelatin gels. Fat droplet clustering was induced or avoided by changing the temperature at which the emulsion was mixed with the gelatin. Rheological properties of the filled gels were investigated by uniaxial compression. The obtained experimental data show that next to changes in droplet hardness and matrix hardness, also droplet clustering contributes to the gel stiffness; even in the absence of discrete bonds between adjacent droplets. The experimental data was compared with the Kerner model, the Kerner model corrected by the effective volume fraction approach and the Kerner model considering an inhomogeneous distribution of the droplets. The Kerner model gives a good prediction for the gels filled with liquid droplets without clustering. The correction for an inhomogeneous distribution of the droplets best described the influence of emulsion droplet clustering in emulsion-filled gels, showing a quantitative evaluation on the role of droplet clustering in the rheological behaviour of emulsion-filled gels. This may provide guidelines for developing a strategy to control certain product properties.

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