What are the practical applications of nano-foods?
Nanotechnology is the science of the very, very small. Measured in billionths of a metre, nanoparticles are similar in scale to viruses, proteins and antibodies. You could fit thousands of nanoparticles inside just one of your red blood cells, leaving ample room to spare.
Manipulating food at this scale could help to develop lower-fat foods that still taste great, or allow manufacturers to pack more nutrients into otherwise vitamin-free foods. This technology should not necessarily be alarming, because the human body is already used to dealing with nanoscale food. Our guts break what we eat down to nano-sized chunks so that the body can absorb nutrients in the intestine, for example.
Nanotechnology is also poised to create better food packaging. It could reduce the amount of plastic used, for example, or make containers smarter by building in sensors that tell us whether the food inside is still fresh.
The food industry has unwittingly been using nanotechnology for years. Mayonnaise is an emulsion of tiny particles, where oil and water are forced to mix together without separating. But researchers are now developing techniques that allow these tiny droplets to be precisely tailored, to give them specific tastes or textures. Mayonnaise stays thick and creamy because "there are so many fat droplets that they divide the water into pockets", says Kathy Groves, a microscopist at contract research company Leatherhead Food Research in the UK. That means it is typically 70% fat – far from ideal if you're on a diet.
One way to reduce the fat content below 40% is to add more water, plus some starch to make sure the mayonnaise does not become too runny. But an altogether tastier approach is to manipulate the droplets' structure on the nanoscale. Groves and her colleagues are developing techniques to replace the insides of the fat droplets with water, creating an emulsion that has the same texture, but less fat than the real thing.
Researchers are also developing nanometre-sized grains of salt, roughly a thousand times smaller than normal table salt. Carving up a grain of salt into these smaller particles increases its surface area a million-fold, which means that your food needs far less salt to give your taste buds the same savoury kick. That could be a boon for those who, worried about high blood pressure, are trying to reduce their salt intake.
As for packaging, nanotech is already being used in the US to stop beers going flat. Plastic beer bottles used by brewer SABMiller contain flaky nanoparticles of clay, which fill up much more space in the walls of the bottle than molecules of plastic. That makes it much harder for fizzy carbon dioxide to escape from the beer – or for oxygen, which can spoil the beer's flavour, to get in. In future, smart nano-packaging might be able to change colour if it detects the gases given off by spoiling food, allowing consumers to make informed decisions about what's safe to eat.