The global market for organic produce is growing at a rapid rate, with market values tripling between 2002 and 2011 when the market was worth an estimated €27.6 billion, said the research team behind the new study. Writing in the Journal of Agricultural and Food Chemistry, the German authors tested the ability of a technique called nuclear magnetic resonance spectroscopy, which has been used to authenticate foods, including honey and olive oil, to differentiate between organic and conventionally grown tomatoes.
Led by Monika Hohmann and her colleagues from the Bavarian Health and Food Safety Authority and the Wuerzburg University, the team devised a new methodology for testing organic produce using nuclear magnetic resonance spectroscopy (1H NMR) – finding that the new method was able to accurately distinguish whether more than 350 samples of tomatoes were organic or conventional produce.
“Because consumers are prepared to purchase organic food at higher prices, the risk for conventional produce fraudulently labelled as “organic” has also been increasing,” wrote the research team. “To prevent and detect counterfeit, there is a strong need for analytical methods that allow the verification of organic cultivation.”
“Linear discriminant analysis demonstrated good discrimination between the growing regimens, and external validation showed 100% correctly classified tomato samples.”
Over a seven month period Hohmann and her colleagues analysed 361 tomato samples from two different cultivars grown in greenhouses and outdoors, with either conventional or organic fertilizers.
Analysis of the results from this principal component analysis ‘showed a significant trend’ for the separation between organically and conventionally produced tomatoes, said the team.
Indeed, external checks to validate whether samples were organic or conventional showed 100% with the analysis results.
“Further validation studies, however, also disclosed unexpected differences between individual producers, which interfere with the aim of predicting the cultivation method,” noted the team.
They concluded that the study results indicate significant differences between 1H NMR spectra of organically and conventionally grown tomatoes.