**2.3 Headspace solid-phase micro extraction (HS-SPME)**

The headspace spontaneous volatile emissions of the two vicia faba cultivars were sampled by means of HS-SPME. Three replications were considered for each legume. The sample was kept at room temperature for 30 min. A Solid Phase Micro-Extraction (SPME) device (Supelco, Bellefonte, PA, USA) covered with poly-dimethyl-siloxane (PDMS, 100 μm) was used, adapted according to the fabricator instructions. After that, the fiber was removed and transmitted to the injection port of the GC-MS system. All the desorption conditions were the same for all the seeds. Furtheremore, blanks were conducted before starting the first SPME extraction. Quantitative comparisons of relative peaks areas were assessed among the same chemicals in the different samples.
