<h4>Stable isotope ratio analysis</h4>
Stable isotope ratio analysis can be used to give an indication as to whether a certain food has come from a certain geographic location. This is be done by comparing isotopes.
<h4>What is an isotope?</h4>
An isotope is a variant of a chemical element – oxygen, hydrogen and carbon are all chemical elements and each has naturally occurring variants in slightly different forms. These isotopes can be distinguished by their mass, and used to compare a particular food of claimed provenance with authentic samples of the same food produced in different regions of the UK. If there is a good match it does not prove that the food was produced in the UK but suggests that it could have been. If there is not a good match in results then that would strongly suggest that the food was not produced in the UK and needs further investigation.
<h4>Geology and weather create changes</h4>
The proportion of an isotope or group of isotopes in a particular food might vary because of geological and climatic processes.
For example, crops grown in the UK have a higher proportion of heavy hydrogen and oxygen than the same crops grown in mainland Europe. This is because the proportion of heavy forms of hydrogen and oxygen diminishes with distance from the sea.
Another example is the way in which plants metabolise carbon dioxide results in certain plants being richer in heavy isotopes of carbon. This means the isotopic composition of animals, and meat derived from these animals, reflects where they were reared and the plant material they eat.
More information about stable isotope ratio analysis can be found via the 'External sites' link on this page.