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Formation, structure and functionality of interfaces in food emulsions
Food Process Engineering group Wageningen University and Research – The Netherlands
Wed, Apr. 19th 2017, 11:00-12:00
NIMBE Bat 127, p.26, CEA-Saclay


In many food systems, lipids are present as droplets dispersed in an aqueous phase, i.e., are oil-in-water (O/W) emulsions. As such lipid droplets are typically small (i.e., 0.1 to a few tens of mm), emulsions are interface-dominated systems, with up to several tens of m2 of interface per gram of oil. This has a number of consequences: such a large contact area between immiscible phases leads to a high free energy of the systems, which tend to physically destabilize. In addition, the composition and structure of the interfacial layer largely affect processes that involve both water- and oil-soluble reactants, such as lipid oxidation or lipid digestion. It is therefore important to control these parameters, but this is highly challenging. First, many molecules are located at the oil-water interface in food emulsions: not only emulsifiers (e.g., proteins, phospholipids), but also a number of minor components with various surface activity, for example antioxidants or free fatty acids. Second, these surface-active molecules partition between the interface and the other phases of the emulsion, meaning that their overall concentration does often not reflect their interfacial concentration. Third, the oil-water interface is not necessarily structurally homogeneous, but may present laterally separated domains. Finally, the interface is a dynamic region, and its composition and structure may largely change over time, with e.g., interfacial protein polymerization, or adsorption of lipid oxidation or lipolysis products.

I will present a few recent examples from my laboratory where we control and characterize the oil-water interface in food emulsions to reach desired functionality. A first example relates to how we can investigate the first milliseconds of interface formation (i.e., emulsifier adsorption) at the surface of emulsion droplets, using microfluidic devices. A second example relates to the design of emulsions stabilized by small fat particles, to create interfacial shells with potential dual functionality. I will also show some results related to the construction of interfacial multilayers of biopolymers (whey proteins and pectin) to delay in vitro lipolysis. Based on this work, and on other available examples, I will discuss the implications and limitations for the rational design of functional interfaces in food emulsions.


Contact : Corinne CHEVALLARD


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