## 3 Materials and Methods
### Volatile Profile and Composition Analysis  
Isolation of aromatic compounds was carried out using a headspace solid-phase microextraction (HS-SPME) procedure. A manual SPME holder (Supelco, Bellefonte, PA, USA) with divinylbenzene/ carboxene/polydimethylsiloxane (DVB/CAR/PDMS, 50/30 \(\upmu\)m) fiber (Supelco) was used to extract the volatile substances. Prior to use, the fiber was conditioned in a gas chromatograph injection port at 250 \({}^{\circ}\)C for 1 h. Preparation and extraction of the sample were performed according to [PERSON] et al. (2017) with minor modifications. For each extraction, 1 g of homogenized chocolate sample was placed in a 40-mL glass vial with a plastic screw cap and then 15 mL of distilled water were added. Sodium chloride (0.5 g) and 15 \(\upmu\)L \(\beta\)-ionone were subsequently added to the sample. \(\beta\)-Ionone was used as an internal standard after checking that it was not primarily present in chocolate, separated well from other volatile substances, was stable at high temperatures, and did not react with water. The prepared samples were subsequently heated in a water bath at 50 \({}^{\circ}\)C with temperature control and stirred for 70 min, the first 15 min of which were the equilibration of the components in the vial space and during the remaining time the fiber was introduced and the adsorption of the volatile components to the fiber took place. The SPME fiber was then removed from the vial space and inserted into the gas chromatography-mass spectrometry (GC-MS) injector (230 \({}^{\circ}\)C), where it was exposed for 2 min. The separation and identification of volatile compounds were performed on a Shimadzu GC-17A gas chromatograph (Shimadzu, Kyoto, Japan) with a Shimadzu GC-MS QP-5050A mass spectrometer detector. The GC-MS system was equipped with a SLB-5 ms GC capillary column (Supelco; 30 m \(\times\) 0.25 mm internal diameter, 0.25 \(\upmu\)m film thickness). Helium was used as a carrier gas at a flow rate of 0.7 mL/min, splitless mode was applied, and the following temperature program performed: (1) Initial temperature 40 \({}^{\circ}\)C, (2) rate of 2 \({}^{\circ}\)C/min from 40 \({}^{\circ}\)C to 180 \({}^{\circ}\)C, (3) a rate of 25 \({}^{\circ}\)C/min from 180 \({}^{\circ}\)C to 300 \({}^{\circ}\)C and hold for 1 min. The injector temperature was maintained at 230 \({}^{\circ}\)C and the detector temperature at 300 \({}^{\circ}\)C. The compounds were simultaneously identified using three different analytical methods: Retention indices (RI) with reference to \(n\)-alkanes (C8-C24), GC-MS retention times of authentic chemicals, and mass spectra (authentic chemicals and spectral library collection NIST05 (National Institute of Standards and Technology, Gaithersburg, Maryland, USA). Identification was taken as only tentative if it was based only on mass spectral data. Quantification of the volatile compounds was performed on a gas chromatograph Shimadzu 2010 with a flame ionization detector (FID). The column and chromatographic conditions were the same as those previously reported for the GC-MS analysis. The injector temperature was 250 \({}^{\circ}\)C and N\({}_{2}\) was used as a carrier gas (1 mL/min). Data handling was carried out by means of GCsolution 2.3 (Shimadzu Corporation, Kyoto, Japan).