The study, published in a recent issue of the Journal of Agricultural and Food Chemistry, looked at two types of tomatoes grown outdoors and in greenhouses, with both organic and conventional fertilizers. The researchers analyzed a total of 361 tomato samples over the course of seven months. Using a technique called nuclear magnetic resonance (NMR) spectroscopy, the investigators were able to measure the amount of a wide variety of chemicals and tomato pulp components (such as glucose, citric acid, and cellulose).
The NMR assesses the spin of nuclei in a given substance when it's placed in a magnetic field. The degree to which each nucleus' spin changes in that field is known as its level of "chemical shift." With that, the researchers were able to identify a set of chemical differences between the organically and conventionally grown tomatoes. The substances that showed variations based on how the tomatoes were grown included malic acid (responsible for sour taste), asparagine, glucose, and adenosine monophosphate, among others. As for how this test will translate to other foods, only time — and further research — will tell.
One important thing to note is that this study was based on the EU definition of "organic" foods, but organic labeling standards in the US are notoriously confusing. Previous studies used nitrogen isotopes to determine whether or not crops were grown in organic fertilizer, but that approach isn't foolproof — unlike the new technique, which has potential to reliably reveal fruit fraud. But, maybe next we could try a test that doesn't require smooshing that perfectly ripe tomato into a pulp.