The taste of tiny: Putting nanofoods on the menu
The taste of tiny: Putting nanofoods on the menu
27 May 2010 by Emma Davies
Nanotechnology Topic Guides
Editorial: How to persuade us to swallow nanofood
NOTHING says summer holidays quite like ice cream. On a hot afternoon by the sea, there’s little to beat the simple pleasure of a cooling scoop of your favourite flavour. Can food get much more satisfying than this?
Vic Morris thinks it can, with the help of nanotechnology. He is part of a team tweaking foods to trick the body into feeling pleasantly full long after the final mouthful – and without overeating.
Ice cream that makes you feel full could be just the beginning. Nanotechnology promises even saltier-tasting salt, less fattening fat, and to boost the nutritional value of everyday products. Nanofood supplements could even tackle global malnutrition.
So what is a nanofood? It isn’t just about nanoparticles. Many foods have a natural nanostructure – the proteins in milk form nanoscale clusters, for example – that can be altered on the nanoscale to enhance their properties.
In fact, researchers have been changing the nanostructure of food for years, for example by adding emulsifiers to improve the texture of ice cream. It’s the emergence of technologies such as atomic force microscopy that has changed the game by finally opening a window on the nanoworld. Rather than working blind, Morris can now take a close look at the tiny structures he works on, understand their behaviour and then make changes in a more rational and deliberate way.
These imaging techniques are behind the high-satisfaction foods Morris is helping to develop at the Institute of Food Research (IFR) in Norwich, UK, which promise to help fight obesity by making people feel full before they overeat. Many foods, from ice cream to hollandaise sauce, contain emulsions, in which the fat is whipped into tiny droplets coated with a stabilising layer of proteins. Emulsions were always assumed to collapse in the stomach, but Morris has seen otherwise: some don’t break down until their protein coat is disrupted by the bile salts they meet in the small intestine.
By cross-linking the proteins, the IFR team can strengthen the protein coat and delay the emulsion’s breakdown until the final part of the small intestine, called the ileum. The sudden burst of fats so far down the small intestine triggers the “ileal brake” – the mechanism that makes us feel full. “The body thinks it has a high-fat diet,” says Morris. The team is now looking to apply this approach to real foods.
Hitting the ileal brake isn’t the only way emulsions could be co-opted into helping cut our fat intake. In “diet” versions of many emulsion-based foods, such as mayonnaise, about half of the fat content is replaced with water, making them less satisfyingly creamy. One alternative is to hide that extra water as nano-droplets within each drop of oil so that the mouth experiences less water and more creamy fat. If the idea works as well on the production line as it does in the lab, low-fat mayonnaise might taste and feel exactly like the regular version.
The encapsulation idea has caught the eye of the food industry. “It’s about improving the nutritional value and shelf life of food products without affecting anything else, such as taste or texture,” says Charles-François Gaudefroy, an R&D director at Unilever, which owns numerous food brands.
The food industry is notoriously tight-lipped about products in development (see “Ready for nanofoods?”), and Gaudefroy won’t say what nanofoods Unilever is looking into. Two other food multinationals, Kraft and Nestlé, declined to talk about their research in the area at all. One area they are likely to be working on, however, is finding ways to add extra nutrients to their products by packaging them inside fat or polymer particles.
“We know that the food industry is looking at encapsulating certain ingredients like omega-3 fatty acids, vitamins or minerals,” says Frans Kampers, who researches bionanotechnologies at Wageningen University and Research Centre in the Netherlands. The idea is an attractive one. Oil-soluble nutrients can be poorly absorbed in the watery environment of the gut, with a proportion passing right through the body. Nano-encapsulation converts them to a dispersed form that is more easily taken up (Current Opinion in Colloid & Interface Science, vol 14, p 3). Wrapping them in nano packages also extends their shelf life, masks any unpleasant tastes and, in the case of nano-emulsions, makes them invisible to the naked eye so that they don’t affect a food’s appearance