Evaluation, by GC-FID, of the stability of oregano during its storage after harvest and drying
Résumé
The purpose of this study is to look for marker compounds in the storage of oregano samples. Four analytical protocols (2 extraction conditions and 2 chromatographic separations) were applied to 24 oregano samples. These samples were produced under the following conditions: open field seedlings, organic outdoor cultivation (Sicily, Italy), harvested during the summer, maturity stage: plant with flowers, drying at 26°C (open air) for 48 hours, storage at the producer for a variable period (from 1 to 12 months) before sending and conditioning for analysis. Two batches were thus monitored for 12 months. Two extraction protocols (hexane or methanolic under ultrasound) were applied to the samples. The extracts were analyzed by GC-FID on two columns (DB-17 and ZB-5ms) to highlight any markers related to the history of the samples. A first analysis of the chromatograms obtained on the DB-17 column, after standardization, shows that certain compounds, present in the two extracts and yet to be identified, are linked to the storage period at the producer. This change does not seem to be induced by the temperature itself. The identification of compounds likely to indicate a very long storage of samples will be carried out in GC coupled to a mass spectrometer on the one hand. On the other hand, the standardized chromatograms will be analyzed by chemometrics in order to identify possible other markers.