April 12, 2007 — A new test could help identify fraudulently labeled organic food, say British scientists.
It's based on testing the food for signs of synthetic nitrogen fertilizers, which are banned in organic farming methods.
Alison Bateman of the University of East Anglia in Norwich and colleagues reported their findings in a recent issue of the Journal of Agricultural and Food Chemistry.
There are a number of food tests designed to pick up residues of synthetic pesticides and herbicides that are not permitted in organic farming. But Bateman and her team are developing a test to see whether foods have been grown using synthetic nitrogen fertilizers, based on testing the foods' nitrogen isotope composition.
Conventionally grown lettuce and tomatoes, for instance, contain nitrogen isotope ratios of the kind found in synthetic fertilizers, their research found. The team says this isotope test could potentially be used to detect conventional produce grown using synthetic fertilizers that is fraudulently labeled as organic.
But the test can't say for certain whether synthetic fertilizers have been used. Rather, their test can determine whether it is "unlikely" or "highly unlikely" that a food with a particular nitrogen isotope composition would have been grown without synthetic nitrogen fertilizers. And the test is likely to be more useful for some crops than others, say the researchers.
For example, in their study carrots had the same nitrogen isotope composition whether grown organically or conventionally. Bateman and her team point out one possible explanation is that growing carrots generally requires less nitrogen and are thus conventionally grown carrots are likely to have less synthetic fertilizer applied.
The demand for organic produce is growing globally, not only in major markets such as Europe and North America but also in developing countries. In 2004, the worldwide market value of organic produce reached $27.8 billion.
But the higher prices obtained by producers provides an economic incentive for a few unscrupulous traders to pass off conventionally grown produce as organic.
