## 2 Materials and Methods
### Determination of Fatty Acids by GC-MS Analysis  
The lipids of mushroom samples were extracted in chloroform/methanol (2/1). The final mixture was filtered under vacuum using a vacuum pump (N 810 FT.18, Laboport, KNF, Germany), and the residue was washed with 0.88% KCl. The organic phase was separated and evaporated to dryness using a rotary evaporator (Hei-VAP Precision, Heidolph, Germany). The dried lipids were resuspended in methanol and stored at \(-\)18 \({}^{\circ}\)C until analysis. Fatty acid methyl esters (FAMEs) of the total lipids (0.2 g) were produced by acid-catalyzed transesterification using 1% sulfuric acid in methanol [19; 20]. The methylated fatty acids were determined using a gas chromatograph (GC) coupled to a mass spectrometer (MS) (PerkinElmer Clarus 600 T GC-MS; PerkinElmer Inc., Shelton, CT, USA) as follows: 0.5 \(\mu\)L sample was injected into a 60 m \(\times\) 0.25 mm i.d., 0.25 \(\mu\)m film thickness SUPELCOWAX 10 capillary column (Supelco Inc., USA), at injector temperature 210 \({}^{\circ}\)C; helium carrier gas flow rate 0.8 mL/min; split ratio 1:24; oven temperature 140 \({}^{\circ}\)C (hold 2 min) to 220 \({}^{\circ}\)C at 7 \({}^{\circ}\)C/min (hold 19 min); electron impact ionization voltage 70 eV; trap current 100 \(\mu\)A; ion source temperature 150 \({}^{\circ}\)C; mass range 22-395 \(m/z\) (0.14 scans/s with an intermediate time of 0.02 s between the scans). The FAMEs were identified based on their mass spectra by comparison with those of reference compounds from the NIST mass spectral library (National Institute of Standards and Technology NIST MS Search 2.0). The amount of each fatty acid was expressed as an area percentage calculated from the total area of identified FAMEs.  
Extraction and Analysis of Volatile Compounds by Headspace In-Tube Extraction Coupled with Gas Chromatography-Mass Spectrometry (HS-ITEX/GC-MS)  
The analysis was performed by extraction of volatile compounds by the in-tube extraction (ITEX) technique, followed by their separation and identification using GC-MS [21]. Briefly, the extraction of volatile compounds was carried out by incubating a headspace vial containing an aliquot of sample (1000 \(\mu\)L) at 60 \({}^{\circ}\)C for 20 min under continuous agitation. After the incubation period, a microtrap fiber (ITEX-2 TRAPTXTA, Tenax TA 80/100 mesh) was inserted into the headspace of the vial, and the volatile compounds were adsorbed continuously (30 strokes) with a headspace syringe (CombiPAL AOC-5000 autosampler, CTC Analytics, Switzerland). The volatile compounds were thermally desorbed directly into the GC-MS injector. The separation and identification of volatile compounds was carried out on a GC-MS system (QP-2010 model, Shimadzu Scientific Instruments, Kyoto, Japan). The separation was performed using a Zebron ZB-5 ms capillary column of 30 m \(\times\) 0.25 mm i.d and 0.25 mm film thickness. The carrier gas was helium, 1 mL/min, split ratio 1:20, injector temperature 250 \({}^{\circ}\)C. The temperature program of the column oven was 40 \({}^{\circ}\)C (held for 5 min) to 50 \({}^{\circ}\)C at 4 \({}^{\circ}\)C/min, then to 250 \({}^{\circ}\)C at 10 \({}^{\circ}\)C/min (held for 5 min). The MS detection was performed on a quadrupole mass spectrometer operated in full scan (35-350 \(m/z\)) electron impact (EI) at ionization energy of 70 eV. The volatile constituents of the samples were identified based on their mass spectra, by comparison with those of reference compounds from NIST27 and NIST147 mass spectra libraries (considering a minimum similarity of 85%). The relative percentage of each compound was estimated as a fraction of its integrated ion area from the total ion chromatograms (TIC) area (100%).