A UK company has developed a highly-sensitive technique for testing whether foods contain genetically-modified ingredients. RHM Technology, based in High Wycombe, believes its new test is far more sensitive than any other method currently in use.

As the row over GM food has intensified, the issue of testing has become an important one. Ethical, health and environmental concerns have led many groups to demand better labelling on foodstuffs.

This requires a precise way of detecting and measuring the chemicals signatures left in products by the processes of gene modification.

This has proved difficult. In a standard test, a sample is scrutinised for stretches of DNA that come from genes that do not occur naturally in the foodstuff.

Processed food

Although, detecting genetic modifications in raw or lightly processed food is straightforward. It becomes more problematic when testing highly processed foods.

GM soya: Used to produce many foodstuffs

Processing and cooking can destroy the sections of DNA being sought.

It also creates numerous types of small molecules that can interfere with the reaction used to amplify the sample for analysis. This can lead to false negative and occasionally false positive results.

The new test from RHM Technology claims to overcome these difficulties. It looks for smaller fragments of DNA which are more likely to survive processing.

Special resin

Confusion caused by small molecules is reduced after the sample is purified and washed in a special resin.

RHM Technology says it can also estimate the percentage of the ingredients that are genetically modified.

"That is an important leap forward," Bob Marsh, the company's managing director, told the BBC.

The new test will be welcomed as the European Union is currently considering its position on the threshold levels used to determine whether foods need to carry a GM label.

New thresholds

It is expected to introduce rules that would allow food to be labelled as GM-free if they contained soya or maize that had less than about 2% GM ingredients. This will prevent companies being blamed for accidental contamination.

RHM Technology is owned by Ranks Hovis McDougall, but it will be making the test available to its rivals in the food industry.

"This test will enable the establishment of thresholds," Bob Marsh said.

"We are able to take in samples for testing from other groups because we are not competitive on testing - RHM is just competitive in the way it manufactures its food products."

The new test is featured in New Scientist Magazine.