## 3 Results
### Aroma Composition of Beers Dry-Hopped with Selected Samples  
Twelve key aroma compounds from hops that would be expected to be transferred to beer during the dry-hopping process were selected and quantified in beers. Esters, terpen and sulphurons compounds have been cited by various authors as key hops compounds relevant to flavouring beers by dry-hopping techniques [18; 22; 23; 24]. Therefore, seven esters (ethyl 2-methylpropanoate, 2-methylbutyl 2-methylpropanoate (2 MB2 MP), 3-methylbutyl 2-methylpropanoate (3 MB2 MP), ethyl 2-methylbutanoate, ethyl 2-methylbutanoate, ethyl 4-methylpentaoate, and ethyl cinnamate), two monoterpens (mycrene and geranyl acetate), two monoterpenoid alcohols (linalool and geraniol), two sesquiterpenpens (\(\beta\)-caryophyllene and \(\alpha\)-humulene), one sesquiterpenoxide (humulene oxide), one thiol (dimethyl tivalphide (DMTS)), and two thioesters (S-methyl 5-methylpentanthioate and S-methyl hexanthioate), making a total of 12 compounds, were quantified in the four dry-hopped beers. Concentrations and thresholds (\(\mu\)g/L) of volatile compounds in non-dry-hopped beer and beers dry-hopped with Portuguese wild hops are summarized in Table 3. Overall, the results obtained after compounds quantification agree with the sensory analysis. Significant differences (\(p<0.05\)) were observed in the volatile compounds content of dry-hopped beers when compared with non-dry-hopped beer, which can explain the increased total hoppy impression in the sensory analysis. Regarding the monoterpenes, PT05 and PT15 hops promoted concentrations over the threshold levels for mycrene and the monoterenoid alcohols linalool and geraniol (only PT05), but PT11 and PT14 were the hops that imparted the highest concentrations. Significant increases of monoterpene mycrene (in both beers)  
Figure 2: Quantitative descriptive sensory analysis of beers dry-hopped with Portuguese wild hops. Each beer score is represented by a different colour. PT05 (blue), PT11 (red), PT14 (yellow), PT15 (green), and non-dry-hopped beer in the grey area. Data from sensory analysis performed by trained panellists are presented as means (floral) in normal distribution or medians (other attributes) in non-normal distribution. Two independent samples t-test and Mann-Whitney test were applied to detect which attributes were significant in normal and non-normal distributions. Letters between brackets represent that (**a**) PT14, (**b**) PT11, (**c**) PT05, and (**d**) all hops presented significant statistical differences (\(p<0.05\)) of the attribute in comparison with non-dry-hopped beer. and the monotorepenoid alcohols linalool (in both) and geraniol (in PT11 dry-hopped beer) were observed. These compounds have been described with positive correlation to the intensity of hoppy aroma in dry-hopped beers [11; 25]. In addition, PT11 and PT14 beers were the only ones that presented significant increases with values over the threshold of esters. The results obtained can explain the fruitiest sensation of these beers (Figure 2), since this class of compounds has been associated with hop-derived fruits characteristics of beers [11; 26; 27]. Therefore, PT11 presented the highest contents of ethyl 2-methylbutanoate, ethyl 3-methylbutanoate and ethyl 4-methylpentanoate,  
\begin{table}
\begin{tabular}{c c c c c c} \hline
**Compound** & **NDH Beer** & **PT05 Beer** & **FT11 Beer** & **PT14 Beer** & **PT15 Beer** \\ \hline
**Esters** & & & & & \\ Ethyl 2-methylpropanoate & 0.19(0.15-0.23) \({}^{\ast}\) & 0.69 (0.59–0.79) \({}^{\text{h.c.}}\) & **1.30 (1.03–1.57) \({}^{\text{cd. }}\)** & **2.34 (2.25-2.43) \({}^{\text{d.}}\)** & 0.33 (0.32–0.34) \({}^{\text{ab. }}\) \\ \hline Ethyl 2-methylbutanoate & 0.022 (0.020–0.025) \({}^{\ast}\) & 0.17 (0.17–0.17) \({}^{\text{h.c.}}\) & 0.36 (0.34–0.38) \({}^{\text{c.}}\) & 0.13 (0.11–0.15) \({}^{\text{ab. }}\) & 0.15 (0.13–0.16) \({}^{\text{ab.