For generations, children have marvelled at the magical concoctions in Willy Wonka's chocolate factory. Everlasting gobstoppers, a chewing gum that tastes of a three-course meal and ice cream that doesn't melt - each piece of confectionery was more elaborate and beyond the bounds of credibility than the last.

Or was it? Almost half a century after Roald Dahl charmed children worldwide with his tale of Charlie and the Chocolate Factory, food companies are turning to the controversial science of nanotechnology to develop products Wonka would be proud of. "Pretty much every major food and drink company has a long-term plan for nanotechnology," confirms Victor Morris, scientist at the Institute of Food Research in Norwich.

If they pursue their plans, however, they will be running the gauntlet of the growing number of sceptics who believe nanotechnology could be dangerous to human health. Last month the Soil Association banned nanoparticles from its certified products and this month Which? will hold a seminar on the science, so concerned is it about the dangers it could pose.

So is the industry right to push ahead or are experts' fears that nanoparticles could lead to the creation of harmful 'Frankenfoods' well founded?

Nanotechnology is the engineering of materials at an incredibly small scale - at nanometre level, to be precise, which is a millionth of a millimetre. It allows scientists to look at how the molecular structure of food alters during the cooking process, how the particles are digested in the gut and how to improve their qualities.

"We use the information we get from looking at particles on a nanoscale to select better raw materials and develop better products," says Morris.

At the moment, UK consumers may be able to buy razor blades with a carbon nanocoating for extra strength and socks that contain nanoparticles to help people with excessively sweaty feet, but when it comes to food, the options are pretty limited. Though the micro and nanotechnology industry in the UK more than doubled from £11bn in 2004 to £23bn in 2006, only about 50 or so of the 600 products globally said to contain nanoparticles are food or drink products.

At the moment, it remains an embryonic science when it comes to food and most nanotechnology-related NPD is very much work in progress. There have been a number of early adopters, however.

Kraft Foods is developing 'programmable foods' such as a clear drink that can be hundreds of different flavours depending on consumer preference. Soft drinks companies such as Coca-Cola and PepsiCo are believed to be developing beverages whose colour and fizz can be adjusted by the consumer at home, while Mars has a patent in the US for edible coatings for lines such as M&M's and Skittles that could hugely extend their shelf life.

Unilever is so interested in the science, meanwhile, that it is sponsoring conferences and events on the subject. While it says it isn't developing anything specific, it believes nanotechnology will play an important role in food in the future.

"We want to be part of the discussion and at the forefront of new research so when something really important breaks we will be the first to get it," says one of the company's scientists.

However, it is playing its cards close to its chest when it comes to divulging what progress it has made with NPD. "We don't want to speak about something that is hypothetical," the scientist adds. "We want to have something developed and tested before we talk to the consumer."

The truly wild and wacky products will not be available for some time, says Franz Kampers, researcher at the Netherlands' Wageningen University and Research Centre. In the short term, food and drink companies are more likely to use nanotechnology to improve or fortify existing products.

It could be used to encapsulate nutrients in an agent that disintegrates at a specific point in the body for targeted nutrition, for example, preserving nutrients that would not normally survive the manufacturing process. The university is also working on is 'nanonaise', a low-calorie mayonnaise made by manipulating membrane emulsions in mayonnaise at the nano level. The result, claims Kampers, is a product that has the taste and texture of mayonnaise but has dramatically fewer calories. Despite its denials, Unilever is reportedly looking to use a similar process to produce low-fat ice cream.

And the technology is also being used in the development of packaging. RFID tags use the technology, as do labels that change colour to show when fruit is ripe. US beer giant Miller Brewing is using beer bottles that contain clay nanoparticles to make them less likely to shatter.

This, h0wever, is arguably the acceptable face of nanotechnology. When it comes to manipulating the food itself, manufacturers are wary of telling consumers about products at too early a stage, says Morris. "A lot of companies are working behind closed doors so when they make a product they can answer all consumers' questions and show them the benefits."

Their concerns are understandable. Though humans breathe in millions of naturally occurring nanoparticles each day, some experts fear that man-made nanoparticles could be harmful. Some natural particles, for example, when broken down to nanoscale, take on new properties. So an inert metal such as gold, which is used in some drinks, can trigger chemical reactions when used on such a small scale. What impact these new particles have on human health and the environment is still relatively unknown.

Even the Centre for Responsible Nanotechnology's website says that although nanotechnology "carries great promise... unwise use could seriously threaten the survival of the human race".

Sue Davies, chief policy adviser at Which? echoes this sentiment. "There are exciting benefits for nanoparticles but a lot is still unknown about those that are manufactured," she says. "More work is needed to assess the risks. We don't have the methodology to come to any conclusions on exposure of nanoparticles."

The consumer association, which is holding a summit on the issue this month, is concerned by the level of public ignorance. It claims 61% of people haven't heard of the science and that more than a third of those who have are unaware it is being used to develop consumer products.

"There needs to be much greater openness from the industry," says Davies. "Consumers need to get an idea for what types of products are coming in the future. It is very difficult for them to understand the benefits if they don't know what is being developed and why. When people are kept in the dark there is a risk that the industry could face a GM-style backlash."

Another problem is that the regulatory framework is not equipped to deal with nanotechnology, she says.

Current EU regulation requires all food and drink products sold to be "safe", but this does not go far enough, she claims. "How do we know if nanoparticles are safe? It is impossible to make generalisations about nanoparticles. There are regulatory gaps in assessing the safety of individual products that need to be closed."

The UK government has provided £10m for research into the science in the past three years and says "significant progress" has been made in understanding the effect of human exposure to nanoparticles. However, it admits that gaps in understanding remain. Those gaps were enough for the Soil Association to implement its ban.

"There should be no place for nanoparticles in food," says policy manager Gundula Azeez. "We are deeply concerned at the government's failure to follow scientific advice and regulate products."

Predictably, Dr Steffi Friedrichs, director at the Nanotechnology Industries Association, which promotes the responsible use of nanotechnology, takes a different view. "Some particles may be hazardous if inhaled but there are those that never pose any risk of exposure," she says. "There is no risk if there is no exposure, so the whole question of risk needs to be fully addressed."

One way to get consumers on board, she says, is to make them understand the role nanoparticles already play in everyday life. Milk contains emulsions and when it becomes homogenised the fat is broken down to nanometre size, for example, she says. Tea is just nanoparticles floating in water, she adds.

Another, say advocates, is to carry out research that demonstrates how safe the science is. Napier University in Edinburgh is doing just that. It is currently conducting a government-funded research project looking at whether humans can absorb nanoparticles from food and skincare products and whether they are toxic to the gut. Initial results indicate that many nanoparticles are safe for humans.

"I am unaware of any data that shows conclusively that any nanoparticles included in food can enter the [human] body via the gut," says Professor Vicki Stone, who is overseeing the project. In tests on animals, a small number of particles have been absorbed from the gut into the bloodstream, but no adverse health effects have as yet been linked to this exposure, she says, adding that she is confident nanoparticles will eventually be shown to be safe.

"Many studies are focusing on the physical and chemical characteristics of nanoparticles to see how these influence safety and toxicity. Once we understand what makes them safe or toxic, I have no doubt that they can be used safely."

Morris is equally optimistic and believes that it is only a matter of time before nanotechnology plays a major role in NPD. At the moment it is an embryonic science that food companies are reluctant to speak about, perhaps because they fear a similar consumer backlash to the one faced by GM foods, but its use could be widespread.

Ultimately, the future of nanoscience rests on whether the industry can convince consumers it is safe, something which Morris believes will happen. "You need to introduce public debate but in the future it will be embraced," he says.

If it is, the science of small could soon be massive.nScience under scrutiny

Nanotechnology is the understanding and control of materials at nanometre level

A nanometre is one-millionth of a millimetre. A sheet of paper is about 100,000 nanometres thick

The concept was born in 1959 when physicist Richard Feynman suggested building machines small enough to manufacture objects with atomic precision

Nanoparticles can be naturally occurring. Some are toxic.

The US has the most products that use nanotechnology, followed by Korea and the UK

More than 50 food and drink products claim to use nanomaterialsNanoproducts on the market

US company Nutrition by Nanotech produces Nano B-12 Spray - a "candy tasting" spray of Vitamin

B-12 nanodroplets - for adults and kids

Slim Shake chocolate milkshake, also available in the US, uses nanoclusters 100,000th the size of a grain of sand to carry nutrition to cells

L'Oréal markets anti-ageing skincare products such as Revitalift that contain 'nanosomes'. It describes these as "nanoscopic vehicles that deliver active ingredients to the skin in as specific and long-lasting a way as possible"

UK company Nanogen sells hairloss products that contain 'nanofibres'. The microscopic fibres bond to hair fibre to improve hair coverage

German manufacturer Henkel sells Theramed SOS Sensitive toothpaste that contains Nanitactive, an ingredient made up of nanoparticles and protein that mimics the components found in teeth

JR Nanotech of the UK sells SoleFresh socks, which contain Nano-Silver particles to prevent bacteria and fungus that can cause itchy and smelly feet

Canola Active Oil, developed by Israeli company Shemen Industries, contains nano-sized cells that carry vitamins, minerals and phytochemicals that are insoluble in water or fat