## 3 Results and Discussion
### Fermentation Kinetics and Basic Parameters of the Obtained Beers
Roasted aromas (including such aroma notes as malty, worry, caramellic, bready and yeasty) accounted for almost half of all aromas detected during the olfactometric analysis of the hopped wort used for fermentation (Table 2, Figure 2). The Maillard Reaction Products (MRPs) are essential contributors to malt flavour and colour [26]. The literature shows that some Strecker aldehydes, particularly 2-methylbutanal, 3-methylbutanal, benzeneacetaldehyde and methional, have an important role in the attributes associated with flavor of wort. These aldehydes have exceptionally low odor thresholds and impart potent worry, malty, and cocoa-like aromas even at low concentrations [27]. This was indeed confirmed by our research, i.e., four components--Strecker aldehydes (methional, 3-methylbutanal and benzeneacetaldehyde) and other MRPs (such as maltol) were in the top five most intense aromas during olfactometric analyses of the prepared hopped wort (Figure 2). Such an intense aroma of methional may be a characteristic feature of worts obtained from malt extract. [PERSON] et al. [28] showed that malt is the main source of aging aldehydes, such as methional, introduced into the wort during the boiling process and its level increases during storage. Therefore, it should be assumed that malt extract, usually stored long before use, may be a potentially important source of this type of substance. Methional is characterized by the aroma of boiled potatoes and in higher concentrations is negatively correlated with the aroma quality of beer [29]. Despite the high intensity of the aroma in the olfactometric analysis, this compound did not negatively affect the aroma of the wort (Figure 3) or produced beers (Figure 4). The second most intense aroma in the hopped wort was 3-methylbutanal (3-MB). Together with 2-methylbutanal (2-MB), it is an important aging compound and wort off-flavor with a typical sweet, bread-like aroma [30]. Benzeneacetaldehyde (sweet and cocoa), maltol (sweet and caramellic aroma) and 5,5-dimethyl-2(5H)-furanone were also significant for the aroma of the wort, resulting from the Strecker degradation. The key aromas of hopped wort also included vanillin with a sweet, vanilla-cream aroma. \begin{table}
\begin{tabular}{l c c c c c} \hline \hline
**Compound** & **\(\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{ }}}}}}}}}}}}}}}}\) & & & & \\ \hline
3-Methylbutanal & 634 & 44 & 0.2 & 9.7 & 48.3 & Bready, fruity [R] \\ \hline
2-Methylbutanal \({}^{\text{s}}\) & 650 & 44 & 12.5 & 5.0 & 0.4 & \\ \hline
2,3-Pentanedione & 675 & 43 & 900 & 1.6 & 0.0 & Sweet, cheessy, bready \\ \hline Dimethyl disulfide & 734 & 94 & 0.16 & 1.4 & 8.8 & Sulfurons, earthy, mushroom [E] \\ \hline Furfural & 815 & 96 & 250 & 2.5 & 0.0 & \\ \hline
3-Methylbutanoic acid & 831 & 60 & 22 & 2.9 & 0.1 & Earthy, mushroom, cheessy [E] \\ \hline Methional & 894 & 48 & 0.2 & 6.5 & 32.5 & Boiled potatoes [V] \\ \hline
5.5-Dimethyl-2(5H)-furanone \({}^{\text{s}}\) & 908 & 97 & 3.4 & & Worry [R] \\ \hline Benzaldehyde & 926 & 77 & 350 & 1.2 & 0.0 & \\ \hline Dimethyl trisulfide & 945 & 126 & 0.005 & 0.9 & 178.8 & Sulfurons, cooked onion [V] \\ \hline Hexanoic acid & 963 & 60 & 3000 & 2.9 & 0.0 & \\ \hline Octanal & 979 & 43 & 0.7 & 3.6 & 5.2 & Aldehyde, solvent [C] \\ \hline \(\beta\)-Myrcene & 1000 & 93 & 13 & 0.8 & 0.1 & \\ \hline Benzeneacetaldehyde & 1029 & 91 & 4 & 23.9 & 6.0 & Green, sweet, cocoa [FR] \\ \hline
2-Ethly-1-hexanol \({}^{\text{s}}\) & 1045 & 57 & 270000 & 3.8 & 0.0 & \\ \hline Acetophenone & 1042 & 105 & 65 & 4.5 & 0.1 & \\ \hline
1-Octanol & 1068 & 56 & 110 & 0.8 & 0.0 & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The key aroma components of hopped wort used for the fermentation.