Tunable oleosome-based oleogels: Effect of polysaccharide architecture on polymer bridging-based structuring

Abstract

A simple method for structuring natural oleosome emulsions by polymer-bridging mechanism is proposed. Polymer bridging of oleosome droplets was induced by the addition of two different adsorbing polymers. Over a range of polymer/oleosome ratios, the mixture results in the formation of a particle gel network of aggregated oleosome droplets. It is found that polymer bridging ability is heavily influenced by the strength of binding between polymer and oleosome surface where sodium alginate interacted stronger to oleosome surface than ι-carrageenan. These effects are associated with the different molecular architecture and physical differences between the two hydrocolloids. Alginate has a co-block arrangement of charged and uncharged units. The polymer promotes stronger adsorption to the oleosome surface, in contrast to ι-carrageenan, where the negative charges are distributed uniformly along its chain. The polymer bridging ability will influence the resulting microstructure and therefore rheological properties. Confocal scanning laser microscopy showed that the difference in microstructure is mainly in the extent of heterogeneity over different length scales where sodium alginate produced the most heterogeneous microstructures. Bridging-flocculated emulsions showed power-law scaling behavior of the storage modulus with the oleosome concentration, which was explained using percolation theory.