Scientists have developed a new snack with a little extra bite - radioactive crisps.

But do not worry, these will not be on sale in the local supermarket. They have been designed to help get a better understanding of how food ingredients mix and move as they make their way down a production line.

When the potato snack is manufactured, the flavouring is typically added in the form of a powder to a rotating drum containing the crisps. By tracking the movement of a crisp that has been specially labelled with radioactive particles, the researchers can work out how evenly the flavouring is distributed in the snack.

"Many of the 'fluids' processed in the food industry have strange flow properties that cannot easily be predicted," Dr David Parker from the University of Birmingham, UK, tells Physics World magazine.

"To counter this lack of knowledge, the fluids are generally processed for longer than necessary, which often proves expensive and may affect the quality of the final product."

Yoghurt and ice cream

Dr Parker and colleagues in the university's Positron Imaging Centre are using the technique to study other foods including molten chocolate, yoghurt and ice cream, together with many other granular and viscous fluids used in a variety of industrial processes.

The radioisotopes attached to the crisps are proton rich and undergo a form of beta decay that results in the emission of a positron, a sub-atomic particle that is similar to an electron but has a positive charge. When it meets an electron, the two are annihilated and gamma rays are released. It is this high-energy radiation that is then picked up by the research team's positron emission particle tracking (PEPT) camera and identifies the location of the tagged crisps in the mixing drum.

The camera is mounted on rails and can move to different locations to track the movement of the crisps.

"During studies like this, our lab becomes rather hectic, with buckets of crisps flying in all directions," says Dr Parker. "In decontaminating the lab afterwards, radioactivity is the least of our problems."

The Positron Imaging Centre has acquired a new camera at a cost of over £300,000, funded under the UK's Joint Research Equipment Initiative. The equipment is more sensitive and should allow more detailed analysis of more complex and faster moving systems.