## 2 Materials and Methods
### Gas-Chromography for Quantification of Beer Volatile Compounds and Olfactory of Hops  
Volatile compounds were extracted by way of headspace solid-phase micro-extraction. Beers (5 g) and hops (0.5 g) samples were placed in 20 mL headspace vials with polypropylene caps (Butyl/ PTFE, Achroma, Muhlheim, Germany) exposed to a divinylbenzene/ carboxen/polydimethylsiloxane (DVB/CAR/PDMS) SPME fibre 50/30 \(\upmu\)m (Supelco/Sigma Aldrich, Bellafonte, PA, USA) for 30 min at 40 \({}^{\circ}\)C and were analysed with gas chromatography-mass spectrometry-olfactometry (GC-MS/O) [17]. \begin{table}
\begin{tabular}{c c} \hline \hline  & **Attributes** & **Standard References** \\ \hline
**Hop References** & **Attributes and Descriptions 1** \\ \hline Ariana & Fruity: black berries, blackcurrant, peach, pear, tropical fruits, resinous, \\  & grapefruit, strawberry, quince, green pepper, banana \\ \hline BravoTM & Citrus and herbal: orange, fruity, vanilla, floral, chrysanthemum, vanilla \\  & cream, vegetable, calendula, butter \\ \hline Hallertauer Blanc & Fruity and spicy: white wine, coffee, cassis, gooseberry, grapefruit, lemon \\  & grass, elderflower, grapes \\ \hline Nugget & Fruity, spicy, and resinous: pineapple, lemon, ginger, geranium, \\  & floral, lychee \\ \hline Hallertauer Magnum & Spicy and green fruits: fruity, apple, pepper, lemon, chocolate, green \\  & peppers, mint \\ \hline Hallertauer Taurus & Spicy and fruity: pepper, lime, currant, spicy, plain chocolate, ripe \\  & banana, pepper, curry \\ \hline Hallertauer Tradition & Herbal and citrus: tea, spicy, orange, lavender, cassis, apricot, \\  & citrus, peach \\ \hline Herkules & Citrus, fruity and spicy: pepper, spicy, resinous, orange, honeydew \\  & melon, lemon, melissa \\ \hline Hersbrücker & Herbal and green tea: spicy, hay, orange, tobacco, citrus, black tea, \\  & marjoram, ginger, melissa \\ \hline Hüll Melon & Fruity and sweet: melon, tropical fruit, orange, vanilla, fruit tea, wild \\  & strawberry, geranium, aniseed \\ \hline Mandarina Bavaria & Citrus and fruity: tangering, grapefruit, lime, bubble gum, pineapple, \\  & gooseberry, cassis, strawberry, lemon \\ \hline Opal & Spicy: herbal, pepper, grass, aniseed, citrus, apricot, liquorice, aniseed, \\  & bergamot \\ \hline Polaris & Citrus and fruity: menthol, ice wine, pineapple, pineapple, woodruff, \\  & bergamot, banana, mint \\ \hline Smaragd & Herbal, spicy and resinous: spicy, aniseed, tobacco, clove, cognac, \\  & camomile tea, liquorice, tarragon, butter \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._Chromotographic analysis was performed in the gas chromatograph system TRACE 1300 Ultra, directly coupled with an ISO QD single quadrupole mass spectrometer (ThermoScientific, Waltham, MA, USA) equipped with an injection split/splitless port associated with a selective detector mass, EI mode at ionization energy of 70 eV. The GC-MS was equipped with a Trace GOLD TG-5 MS (ThermoScientific Waltham, MA, USA) column (60 m \(\times\) 0.25 mm \(\times\) 0.25 mm). After volatiles extraction, HS-SPME fibre was desorbed (manually) in the injection port at 250 \({}^{\circ}\)C for 0.5 min in splitless mode. For the chromatographic separation, the GC oven temperature started at 60 \({}^{\circ}\)C, was held for 4 min, increased at 5 \({}^{\circ}\)C per minute to 220 \({}^{\circ}\)C, held for 5 min and heated to 250 \({}^{\circ}\)C at a rate of 10 \({}^{\circ}\)C per minute and the final temperature was held for 2 min. The transfer line was set to a temperature of 250 \({}^{\circ}\)C. The mass spectrometer detected mass ranges between 35 and 350 \({}^{\circ}\)u. The chromatographic separation had a constant flow of 1.2 mL/min using helium BIP as a carrier gas. The retention index (RI) of each compound was calculated using the retention time (RT) of that compound compared against the RTs of a series of standard n-alkanes.