Emulsions such as mayonnaise are becoming low-fat, tastier and more sustainable thanks to a promising new technology. This has been developed by Koen van Dijke, who until recently worked in the Food process engineering group. Koen received his PhD on Friday 13 November for his thesis on Emulsification with microstructures.
Emulsions are suspensions of fluids that do not naturally mix, such as oil and water. With the right tricks, two non-combinable fluids can be mixed to form a homogenous mass, or emulsion. It's hard to imagine a food industry without emulsions any more. Every day we make use of countless emulsions, in milk, in margarines, ice creams, custards and salad dressings. 'Traditional methods used brute force to get the two fluids to mingle until one of them was dispersed through the other in the form of minuscule droplets', explains Van Dijke. 'But that costs a lot of energy and the result is by no means always optimal.'
Van Dijke followed the droplet formation using high-speed cameras. He also carried out computer simulations to get a better understanding of the process. Van Dijke: 'Six interconnected computers were sometimes busy for a week working out the effects of, for example, the viscosity of the fluids used on the droplet formation.' On the basis of the insights this generated, Van Dijke developed a new system for emulsion formation. 'We developed a system on a micro scale, letting a very thin film of oil run into water', says Van Dijke. 'As the oil enters the water, droplets form at a rate of two thousand per second, and mix with the water.' The emulsions obtained like this are more homogenous than those obtained with standard techniques, and the production takes less energy.
Van Dijke's technique has other advantages besides energy savings and quality. It is also possible to make a double emulsion: A water-in-oil emulsion is then added to a watery fluid. The oil droplets in this emulsion consist mainly of water. This offers new possibilities for making super-low-fat margarine which tastes the same as the full-fat variety. 'Research shows that the taste of mayonnaise is largely determined by the size and the quantity of the drops', says Van Dijke. 'If you fill the oil drops with water, you still get the same taste.'