Matrix properties affect the sensory perception of emulsion-filled gels

The breakdown properties and sensory perception of emulsion-filled gels with different matrices were studied at varying emulsion concentrations. The gel matrices used were cold-set whey protein isolate (WPI), gelatin, κ-carrageenan and a mixture of κ-carrageenan and ι-carrageenan. The oil-in-water emulsions added to the gels were either stabilised by native WPI or WPI aggregates. The emulsion droplets were homogeneously distributed in WPI gels, slightly aggregated in mixed κ/ι-carrageenan and extensively aggregated in κ-carrageenan gels. For gelatin, gels with equal composition but with either non-aggregated or aggregated emulsion droplets could be prepared by changes in processing conditions. The gel modulus as determined by large deformation experiments increased at increasing emulsion concentration for WPI and gelatin gels, but decreased for κ-carrageenan gels. For mixed κ/ι-carrageenan no effect of emulsion concentration on gel modulus was observed. Based on these observations, we concluded that the emulsion droplets were bound to the matrix in WPI and gelatin gels and unbound in carrageenan gels. Most of the mouthfeel attributes generated by a quantitative descriptive analysis (QDA) sensory panel discriminated between emulsion concentrations and different types of gel matrix. At increasing emulsion concentration the perceived creaminess of the samples increased. For gelatin, κ-carrageenan and mixed κ/ι-carrageenan gels, i.e., for gels melting at the oral processing temperature or containing unbound oil droplets, the creaminess scores were consistently higher than for WPI gels, which were perceived as more rough. For gelatin gels, no effect of oil droplet aggregation on sensory perception was found.