Fat droplet characteristics affect rheological, tribological and sensory properties of food gels

• Gels with unbound droplets increase fat-related perceptions regardless of SFC.
• Increasing droplets in gels increases fat-related perceptions regardless of SFC.
• Above two findings relate to an increase in coalescence and a decrease in friction.
• Increasing SFC in gels further increases coalescence and decreases friction.
• Increasing SFC does not further increases perceptions due to complex gel breakdown.

This work aims to investigate the effect of fat droplet characteristics in emulsion-filled gels on their dynamic rheological, tribological and microstructure properties during breakdown, and their sensory perceptions.Fat droplet characteristics investigated were the interaction of the fat droplet with the gel matrix (modulated by using different emulsifiers to yield droplets being either bound or unbound to the matrix) and the solid fat content (SFC, varying from 4% to 48%). Fat content was varied from 0% to 20%.Elastic modulus and fracture properties of these gels (determined under uni-axial compression) were affected by droplet–matrix interaction, fat content, and SFC. A mouth-mimicking tribometer connected to a CLSM was used to determine tribological properties (friction) and microstructural evolution (fat coalescence) of gels under shear. Gels with unbound droplets led to more coalescence (than bound) and increased fat content also led to more coalescence. The observed increase in fat coalescence related to a decrease in friction, which was also related to an enhancement of the perception of fat-related sensory attributes (determined by quantitative descriptive sensory analysis).The effects of unbound droplets and higher fat content on increasing coalescence and decreasing friction were further enhanced by increasing SFC. Having found that decrease in friction and increase in coalescence relates to an enhancement of perception of fat-related attributes, one would expect that increasing SFC would further enhance the perception of fat-related attributes. This was not found. We attribute this to the fact that our systems are gels that have complicated breakdown behavior.

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