Understanding the factors affecting emulsion stabilization and pathway of lipid oxidation
Emulsion stability is often referred to as physical stability, i.e., the maintenance of small, individual droplets of liquid evenly dispersed within the continuous phase of another liquid. To maintain small droplets, the interface is often stabilized using amphiphilic molecules or hydrocolloids.
The physical stability is not, however, alone sufficient to provide the required shelf-life for perishable products, such as those containing polyunsaturated fatty acids. Unsaturated fatty acids are recommended in human diet due to their health benefits; however, the presence of double bonds in the fatty acid chain makes them prone to oxidization by a radical chain mechanism. Lipid oxidation is undesirable because it decreases the nutritional value and leads to the development of off-flavors (“rancidity”) and the formation of potentially toxic reaction products. This has restricted the incorporation of polyunsaturated lipids into many food products. O/W emulsions are even more prone to oxidation than bulky oil, due to the high oil surface area available for the reactions with oxygen.
We characterize the potential of hemicelluloses to formulate and maintain small droplets of oil in water and prevent lipid oxidation. Our aim is to understand the pathway and factors affecting the stabilization.
Developing superior and stable oleogels
Oleogels (a.k.a. organogels) are lipid-based materials that contain 85 – 99.5% of liquid oil whereas the rest is structuring molecules called oleogelators. They were introduced as saturated and hydrogenated fat substitutes to fight the adverse effects of excessive fat consumption in the diet, such as obesity. Obesity is a global problem that nowadays involves billion of adults and millions of children. Unfortunately, the most promising oleogels are unstable during storage which impedes these materials from becoming the “fat of the future”. Much effort has been directed to improve oleogel stability, i.e. modification of the formulation, application of different cooling and heating cycles, application of shear during oleogel formation.
To obtain oleogels with long storage stability it is necessary to carefully control the forming crystalline network without inducing adverse effects. Such control is not attainable using the state of the art technology used to tailor oleogel and fat structures.
We develop new technologies to obtain oleogels with a customizable microstructure without jeopardizing their health properties (avoiding i.e. oxidation of oil). These new technologies can prolong oleogel storage stability and thus possibly speed up the replacement of saturated and hydrogenated fats in food products.