High internal phase emulsion gels (HIPE-gels) created through assembly of natural oil bodies

A natural emulsion was used to create a high internal phase emulsion (HIPE) gel with elastic properties, indicated by shear elastic moduli between 102 and 105 Pa. The elasticity of the gel network was provided from a 2D-gel network of proteins which were naturally adsorbed at the interface of an oil-in-water emulsion formed after aqueous extraction of oil bodies from sunflower seeds. Extensive centrifugation of the obtained emulsion resulted in a stable ultrahighly concentrated emulsion with an oil volume fraction of 0.91 and a protein content of 2.5 wt% only. This high volume fraction of the emulsion cream was achieved due to the large deformability (low rigidity) of the oil body surface. After formation of the HIPE, the rigidity of the interfacial network was increased by addition of small concentrations of Ca2+ and heating at 72 °C for 10 min. This led to aggregation of the interfacial proteins, thereby forming a 2D interfacial gel providing a space-spanning network. The behaviour of the self-supporting gel exhibited increased elastic behaviour, determined by the increased elastic modulus of the interfacial network. The balance between the low rigidity upon formation and the increased rigidity after formation offers a tempting strategy to produce structured solid matter that contains edible hydrophobic liquids. Additionally, the followed procedure is cost-effective and friendly to the environment.