Influence of clustering of protein-stabilised oil droplets with proanthocyanidins on mechanical, tribological and sensory properties of o/w emulsions and emulsion-filled gels

This study aimed to determine the effect of clustering of protein-stabilised oil droplets with proanthocyanidins on mechanical, tribological and sensory properties of o/w emulsions and emulsion-filled gels. Whey protein-stabilised oil droplets in o/w emulsions were crosslinked with proanthocyanidins, which led to the controlled formation of dense clusters of strongly-interacting oil droplets, in a size range from 2 to 110 μm. With increasing degree of clustering of oil droplets, the viscosity of o/w emulsions increased by up to three orders of magnitude. Clustering of oil droplets decreased friction coefficients. Clustering led to an increase in perceived creaminess, coating and thickness intensity. The changes in fat-related sensory perception were an interplay of both flow- and friction behaviour. In emulsion-filled gelatine gels, crosslinking of oil droplets increased Young's modulus and decreased fracture strain and stress. With increasing cluster size, gels were perceived as harder and more grainy than emulsion-filled gels with non-clustered oil droplets. Creaminess of emulsion-filled gels did not increase upon clustering, as hardness also increased. When Young's modulus and perceived hardness of the gels were matched, gels containing clustered oil droplets tended to be perceived more creamy (not significant, p = 0.07) and significantly less watery than gels with non-clustered oil droplets. We relate these effects to the role of the emulsion droplets as structuring agents and an increase of the effective volume fraction by clustering of oil droplets. We conclude that clustering of protein-stabilised oil droplets with proanthocyanidins in o/w emulsions and emulsion-filled gels can be used to modify flow- and texture properties with positive effects on perception of fat-related sensory attributes.