Improving the functionality of fat crystal-stabilized water-in-oil emulsions

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Many food emulsions such as vinaigrette and cream consist of tiny oil droplets suspended in water. Emulsifiers are important ingredients that help prevent the oil and water from separating. Examples include milk protein and mustard powder. Recently, spurred by their potential for calorie reduction and costs savings to food processors, emulsions kept stable by particles rather than emulsifiers have seen rising interest. This approach has also been gaining traction to stabilize emulsions consisting of tiny water droplets suspended in oil, so-called water-in-oil (W/O) emulsions, which are present in products such as butter and margarine. There have been dedicated efforts to develop and understand particle-based stabilizers in non-food applications such as sunscreens and crude oil, because these particles impart a very long shelf life. In foods, though many types of particles are being explored (e.g., based on starch or protein), such is not the case with fat crystals based on the dearth of knowledge in the scientific literature. As a result, there exists a great opportunity to deepen the knowledge base regarding how fat crystals may behave as emulsion stabilizers, which is particularly relevant as fats are present in many processed foods. To address this, I propose the following four aims to greatly advance the underlying knowledge base regarding how fat crystals interact with the surface of dispersed water droplets in W/O emulsions. Aim 1 will establish the science underpinning the stabilization of W/O emulsions with fat crystals, focusing on the ability of crystals that exist as tiny particles or films to help increase emulsion stability. This process may be greatly controlled by adding different food emulsifiers. Aim 2 will explore the ability of fat crystal particles or films to change emulsion texture and rheology by tuning how they interact with water droplets, also in the presence of emulsifiers. Similarly, aim 3 will resolve how different emulsifiers promote or disturb how fat crystals and water droplets interact to controllably destabilize and release bioactive ingredients incorporated as cargo within emulsion aqueous droplets. Aim 4 will innovate further to reveal how fat crystal-stabilized W/O emulsions behave in a lab-scale digestive system. Addressing these aims will aid in the development of food emulsions with a longer shelf life, lower caloric load, and new textures to facilitate ingestion. The feasibility of the proposed research is supported by the fact that my lab is actively involved in the early stages of all 4 aims and has published initial papers on these topics. The highly-relevant research stemming from these 4 aims will provide greater awareness regarding the mechanisms of interfacial fat crystallization in W/O emulsions - knowledge that is currently lacking and that promises to yield great insights for the development of food emulsions with health-promoting properties.