Several field trials with different vegetable matrices (tomatoes, cucumbers, peppers) were conducted in greenhouses located in Almeria (Southeast Spain), under controlled agronomic conditions, using organic and conventional cultivation methods. Additionally, a pilot cross-contamination study was carried out in a green bean crop cultivated in greenhouse.
Regarding to isotope ratio mass spectrometry (IRMS) results, the analysis of nitrogen (N) as traces from production method, only δ15N data of the edible parts of tomato plants not provided a robust classification model to discriminate between organic and conventionally cultivation practices, since the addition of low or moderate rates of synthetic fertilizers to basal organic fertilization could not be confirmed by this methodology.
HRMS analysis results on pesticides residues control in organic food showed that within the scope of the pesticides analyzed with a multi-residue method (307 in total), 34 different pesticides were detected in a total of 111 commercial samples labelled with organic certification (only 3 authorized pesticides by organic production). Regarding non-authorized pesticides, phosphonic acid was the substance detected more frequently (with 38 detections), followed by the herbicide chlorpropham (6 times), chlorates (5 times) and the fungicide fludioxonil (4 times). In all cases, the concentration levels were below the MRL values established in the EU regulation, in agreement with good agricultural practice (GAP). Thus, the development and validation of pesticide multi-residue methods with LOQs below 10 µg/kg, it is an important factor for a better evaluation and detection of possible fraud in organic crops. Moreover, the cross-contamination study put in evidence that the drift contamination during the production process was very low (100 times lower as average in fruits) comparing to the treated plants. Additionally, these results also showed that the analysis of leaves could comprise a good temporal tracer of the misuse of pesticides.
The high level of selectivity and sensitivity of the HRMS techniques allowed the identification and characterization of natural food components, present at trace levels but able to allow to distinguish between conventional and organic production practices. The combination of multivariate statistical analysis (MSA) of MS profiling data was a useful approach for sample clustering according to farming production systems. However, MS profiling data are limited to specific crops. Therefore, continuous build-up of HRMS databases obtained under controlled agronomic conditions with different vegetable varieties and different geographical locations could facilitate to help ensure the detection of possible fraud cases, the authenticity of organic production, as well as the potential health benefits of organic products.
Finally, the most relevant results obtained in the project have been presented in several International Workshop (FoodIntegrity-2017, EuroFoodChem-2017, RAFA-2017 and Pesticides-2018) as well as in various scientific events (Researcher Night 2017 and The Science Week 2017). Some of these results have also been published in a scientific journal, in Gold Open Access (doi.org/10.1016/j.chroma.2018.03.002). In all cases, during the dissemination and outreaching activities, EU funding (Marie Skłodowska-Curie Actions) was acknowledged.
