DART-MS approaches for metabolomics-based authentication: Challenges in determining the geographical origin of strawberries (Fragaria × ananassa)

Metabolomics-based approaches are a widely used method for determining the origin of food. The aim of this study was to investigate the suitability of metabolomics analysis using direct analysis in real time mass spectrometry (DART-MS) to ascertain the origin of strawberries. In addition, optimization possibilities and limitations were identified by testing different extraction methods, two different sample delivery systems (Quick-Strip and Dip-it approaches), and running some of the measurements in both positive and negative ionization mode proved to be the most suitable. A total of 207 strawberry samples from six countries were measured and classified using random forest with this optimized approach. The classification accuracy was 63.8%, which shows certain limitations of the approach presented. However, another aim of this study was to protect German strawberries from adulteration with foreign strawberries, and this was achieved with a promising accuracy of 90.3%.