## 3 Results and Discussion  
### Fermentation Kinetics and Basic Parameters of the Obtained Beers  
Fermentation is the process when sugars available in the word are converted by yeast into alcohol, carbon dioxide and heat [18]. The _S. cerevisiae_ yeast strain is known especially for excellent fermentation properties, i.e., fast fermentation rate and high ethanol production [19]. In the present study, the _S. cerevisiae_ strain was characterized by the shortest period of adaptation to the new environment and the highest rate of fermentation for the first 2 days of the process (Figure 1). In the case of non-_Saccharomyces_ strains (_W. anomalous_ and _D. bruxellensis_), the adaptation time was longer, and the highest amount of produced CO\({}_{2}\) was observed between the 2 nd and 4 th day of the process. These strains, apart from _S. cerevisiae_, fermented at a similar level from day 2 to the end of the process. This is also confirmed by the ethanol content results presented in Table 1. The ethanol content obtained by individual strains (_S. cerevisiae, W. anomalous_, and _D. bruxellensis_) did not differ statistically. The yeast _W. anomalous_ shows a good ability to utilize maltose under both aerobic and anaerobic conditions [20]. [PERSON] et al. [21] have proven that some wild strains of _W. anomalous_ are able to make better use of maltose during the fermentation process than other commercial brewing yeast. This is also confirmed by the results presented in the article where this strain used over 90% of the maltose available in the word for fermentation (Table 1). On the other hand, the _D. bruxellensis_ strain is capable of producing acetic acid in the presence of oxygen. This feature is particularly desirable in the production of lambic beers, where it is increasingly used [22]. This was also confirmed in the presented article (Table 1), where _D. bruxellensis_ produced the highest amount of acetic acid among all the analyzed strains. The best fermentation properties, and thus the use of the largest amount of maltose and the production of the largest amount of ethanol, were observed in the case of the _S. kudriavzevii_ strain (Figure 1, Table 1). This strain produced the largest amount of CO\({}_{2}\) between the 6 th and 8 th day of the fermentation process. _S. kudriavzevii_ is present in Belgian beers of spontaneous fermentation and is characterized by the rapid absorption of carbohydrates, high ethanol tolerance and the ability to ferment in the absence of oxygen [23]. Strains _H. uwarum_ and _S. paradoxus_ released an average of 2.4 g CO\({}_{2}\)/100 mL during the fermentation process. _H. uwarum_ yeast is characterized by very low fermentation power and efficiency, but it contributes to improving the complexity of the aroma of fermented beverages, such as beer or wine [23]. In the present study, this strain was characterized by a lower amount of carbon dioxide released during fermentation. However, it used approximately 98% of the available maltose and thus produced an ethanol content of 4.31 g/L. The lowest fermentation ability of the brewing word was observed in the case of _Z. billi_ strain. Time of adaptation to the new environment for this strain lasted the longest, and after 8 days of fermentation, they produced approximately 80% less CO\({}_{2}\) than the _S. cerevisiae_ and _S. kudriavzevii_ strains. This strain was characterized by a low maltose fermentation capacity. During the entire process, _Z. bailii_ strain used only 2% of the available maltose, producing a beer with a content of 1.73 g/L of ethanol. Taking into account the current interest in the production of low-alcohol beers due to the constantly developing market and lower tax burdens [24], the analyzed _Z. bailii_ yeast strain shows potential for the production of low-alcohol beers. no turbidities and sediments, characteristic of the wort made from malt. The preparation of the wort from the malt extract significantly influenced its aroma.