Small Fry - Nanotechnology in Food Processing

The use of nanotechnology in food production is an area of growing controversy, one that threatens to match the debate associated with genetic modification, yet the technology promises the appealing potential of more flavoursome and healthy food. With many companies in Europe shying away from this type of research, legislation is moving cautiously amid fears that the methods have not been sufficiently tested to guarantee the food produced can be consumed safely.

The main area of research concerns the encapsulation of flavours in small packages that can be released in the mouth. The particles can also be used to create an impression that healthy food has a satisfying ‘full fat’ flavour. Other major areas concern food preservation, where a thin nanoscale layer protects food from oxygen and bacteria, and intelligent food packaging, which provides information on the condition of the food or even if it has been frozen and thawed more than once.

But despite the perceived benefits, health fears still centre on the way the body processes and absorbs food. Cells are designed to allow extremely small particles to pass through them and a nanoparticle could therefore carry unprocessed content directly through a cell wall. It is the lack of research into these resultant effects that is holding development back.

Another factor pulling in the reigns of nanotechnology is the problem of its definition. According to Richard Jones, Professor of Physics at the University of Sheffield, the most common definition is that of deliberately creating structures with length scales less than 100nm to achieve new effects as a direct result of those scales.

However, this is not universally recognised by certian lobby groups who want the scale extended upwards to around 300nm. On top of this is the general concern about how much food should be processed at all or whether the trend should move back to eating food in its so-called more natural state.

Accounting for taste

One of the most novel uses of nanotechnology is encapsulation "People are experimenting with encapsulating flavours and then releasing them so you get more intense bursts of flavour," says Jones. "What we are talking about is wrapping up the molecules and releasing them in response to a stimulus, such as the warm, wet environment of the mouth."

This type of technology is available at the microscale, but going down in size allows more accurate triggering for the release of the contents. It is also used for delivering supplements, vitamins and other additives as the encapsulation can mask the flavour.

A slightly different variation is to use the increased surface area of nanoparticles compared with a similar volume of macroparticles. This means, for example, a nanoparticle coated with chocolate will give a more fulsome flavour than would normally be expected from that volume of chocolate. The same is true with salt, so some foods could taste more salty despite less salt being used.

Qasim Chaudhry, senior scientist at Defra’s Central Science Laboratory in York, says only very little needs to be used to cause a big effect because of the increased surface area. "So very little salt will give you much more flavour."

Packaging for flavour

Chaudhry notes that while stringent food laws in the EU have contributed to the lack of take up for this kind of product, nanotechnology is being used in food packaging in the form of nanolayers, which create a barrier to prevent moisture or various gases passing in or out. "It can also be used to prevent bacteria or fungal growth," Chaudhry says.

But there has been concern that because the nanolayer may be in contact with the food some particles may migrate. Chaudhry dismisses this, saying that Defra tested two examples of this and found that in one there was no migration and in the other there was an "insignificant amount" of migration. "We saw these as really safe," he says.

Taking this a stage further, nanoscale sensors can be printed onto the packaging to indicate whether it has been torn and the contents exposed. They can also detect whether the package has been frozen and refrozen and analyse the gases emitted by the food to see if it has started to spoil.

This concept is being extended to create 'electronic tongues' made up of an array of sensors to analyse food and detect the presence of harmful bacteria or fungal growth.

Still in the laboratory are nanoscale dirt-repellent coatings to create self-cleaning surfaces for use in abattoirs and meat-processing plants. Such technology may eventually be used in the home, for coating the inside of a fridge.

Nanotechnology – a healthy future?

As to the health issues, despite nanotechnology becoming more widely used in food processing around the world, the European authorities have yet to make a decision. Chaudhry is quick to stress that this does not mean that the European bodies believe there is a danger, just that they think not enough research has been done.

"There is no general statement that says nanoparticles are good or bad for health," he says. "But the body has various membranes to protect it, and these can get through those membranes. But no-one knows what will happen in real life."

He also points out that in countries where the technology is being used there have been no adverse reactions from people consuming the food but pointed out that effects can occur many years later and that there can be a cumulative effect as people consume more food containing nanoparticles.

Another factor that could hold back much of this technology is cost. "The food industry has very low margins," Jones says. "So they will not want to do it unless it is very cheap. And that rules out lots of things that are been done in the laboratories."