Multi-scale structuring of the oil-water interface in fat crystal-stabilized emulsions

点击翻译按钮获取中文摘要

Fat crystallization has a pronounced influence on the formation and quality attributes of food water-in-oil (W/O) emulsions such as butter, margarine, ice cream and low-fat chocolate, where water is dispersed as fine droplets within a continuous oil/fat network. In such products, 'Pickering' triacylglycerol (TG) crystals englobe dispersed water droplets and contribute to product texture and long-term stability against droplet coalescence and visual phase separation. Two recent discoveries in the Rousseau laboratory are paving the way to the systematic structuring of the physical properties of fat crystal-stabilized W/O emulsions at the molecular and microstructural length scales. We have recently shown that it is possible to 'coerce' otherwise surface-inactive fat crystals into crystallizing directly at the surface of dispersed water droplets by using interfacially-adsorbed liquid-state surfactants with a molecular structure compatible with the TGs. Secondly, shear-cooling of fat crystal-stabilized W/O emulsions within a confined environment induces fat crystal agglomeration into spheroidal, cocoon-like microstructures. Our research has led to development of a new form of Pickering-type stabilization where dispersed aqueous droplets are encapsulated within thick crystal shells. Currently in its infancy, a mechanistic understanding of these phenomena is necessary to fully understand and exploit these structured emulsions. Numerous research tools including Raman spectroscopy, rheology and microscopy will be used. My group also proposes the use of synchrotron X-ray diffraction to establish in-situ the true orientation of TGs and surfactants at the emulsion oil-water interface. Together these techniques will permit the dedicated design and construction of innovative structured Pickering-stabilized W/O emulsions at the molecular and microstructural length scales. The fundamental understanding gained will result in better emulsion stability and therefore increased shelf life for foods and other applications. As well, as W/O food emulsions are increasingly seen as vehicles for calorie reduction by food processors, this highly-feasible research will be a novel tool for the development of healthier processed foods.