## 2 Results and Discussion
### Physico-Chemical Properties of Beer  
The basic physico-chemical properties of beers with mango addition were tested by dosimetry, near-infrared spectroscopy, and potentiometry (Table 3).  
All beers with the addition of mango were characterized by a lower pH value than BC. Mango fruits are rich in many organic acids and their pH is lower than the pH of traditional beer. The main organic acids, which are necessary for the proper metabolism of fruit, are malic acid and citric acid [30]. The content of acids in mango fruit changes throughout the ripening process, so there is a possibility that fruit used for MR, MRH, and MHH, which had the lowest pH value from tested beers, were not as ripe as fruit used to produce mango pulp and juice used for MP and MJ.  
The pH of mango beers in this study was similar to the pH of other fruit beers, like beers with cornelian cherry juice analyzed by [PERSON] et al. [31], which achieved a pH level in the range of 3.43-7.71, or fruit beers analyzed by [PERSON] and [PERSON] [10], which also achieved a pH as low as 3.5. PH of the beer. This is related to its microbial stability, because at lower pH, the  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Beer Type 1** & **Dextrin** & **Maltotriose** & **Maltose** & **Glucose** & **Glycerol** \\
**Concentration (g/L)** & **Concentration (g/L)** & **Concentration (g/L)** & **Concentration (g/L)** & **Concentration (g/L)** & **Concentration (g/L)** \\ \hline BC & 34.60 \(\pm\) 0.89 1 ** & 0.24 \(\pm\) 0.12 1 ** & 0.04 \(\pm\) 0.02 1 ** & n.d. & n.d. & 1.98 \(\pm\) 0.04 1 ** \\ \hline MJ & 27.72 \(\pm\) 0.59 1 ** & n.d. & n.d. & 2.31 \(\pm\) 0.14 1 ** \\ \hline MRH & 31.21 \(\pm\) 0.71 1 ** & 0.07 \(\pm\) 0.07 1 ** & 0.03 \(\pm\) 0.02 1 ** & 2.09 \(\pm\) 0.08 1 ** \\ \hline MRH & 29.82 \(\pm\) 0.61 1  & n.d. & n.d. & n.d. & 2.27 \(\pm\) 0.05 1 ** \\ \hline \hline \end{tabular}
\end{table}
Table 2: Concentration of carbohydrates and glycerol in mango beers.  
probability of growth of unwanted microorganisms decreases, so it can be seen as an advantage by a manufacturer. Nevertheless, modification of the technological process to add fruits at a later stage of beer fermentation may increase the risk of beer contamination, so due caution over this additional step in beer manufacture is needed [32]. Analysis of the physico-chemical properties showed that BC and MJ achieved the lowest alcohol content. Beers with mango solids added to them were characterized by a higher alcohol content than BC. It is worth noting that MJ, despite achieving a similar alcohol content to BC, was characterized by a higher degree of fermentation. The main reason for this was probably the composition of fruit juice, which consists of less non-fermentable sugars than typical beer word, so despite diluting the beer, it also decreased the content of carbohydrates that could not be used by yeast. The degree of fermentation is significant in beer brewing technology, because it determines the efficiency of alcohol production; therefore, proper control of that factor is of utmost importance. A higher alcohol content is typical for fruit beers, as was proved in many publications about this type of alcoholic drink.  
Most of the mango beers (MJ, MP, MRH, MHH), despite a similar or higher alcohol content than BC, contained less calories due to the higher degree of fermentation and lower sugar concentration. The real extract of all mango beers was also lower than the extract of BC, which is another factor that can improve beer microbial stability.