*2.5. HPLC Analysis*

The samples of phenolic extracts with the highest content of total phenols from each trial and 2017 (experiment 1 also from 2016) were selected and analysed for their phenolic compound content in the directly infused extracts, and then filtered using 0.22 μm disposable disk filters. Phenolic compounds were determined in a total of 36 samples from all the experiments. The operating conditions were followed according to that previously described by Bessada et al. [28] using a HPLC system (Dionex Ultimate 3000 UPLC, Thermo

Scientific, San Jose, CA, USA) coupled with a diode-array detector (DAD, using 280 and 370 nm as preferred wavelengths) and a Linear Ion Trap (LTQ XL) mass spectrometer (MS, Thermo Finnigan, San Jose, CA, USA) equipped with an electrospray ionization (ESI) source. The separation was made in a Waters Spherisorb S3 ODS-2 C18 column (3 μm, 4.6 mm × 150 mm; Waters, Milford, MA, USA). Tentative phenolic compound identification was made according to their UV and mass spectra and retention times compared with commercial standards when available or using reported data from the literature. For the quantitative analysis of phenolic compounds, a 7-level calibration curve was obtained by injecting known concentrations. The results were expressed in mg per kg of fresh weight (fw), as mean ± standard deviation of three independent analyses. Figure 2.

**Figure 2.** Schematic view of the experiments, including the four field trials reported in this study.
