## 2 Results and Discussion
### Concentration of Volatile Compounds in Tested Beers
In the tested beers, the highest concentration of humulene was found in MP (33.441 \(\upmu\)g/100 mL) and the smallest in BC (25.230 \(\upmu\)g/100 mL). Humulene is characterized by a woody aroma [18]. Another compound, typically found in hop cones and detected in all tested beers, was \(\upbeta\)-myrcene. Humulene is a compound found in many aromatic plants, such as pine, saliva, ginger, and cumin. It is a component of many essential oils [19]. It was found in all tested beers, in the greateest amount in MP (68.384 \(\upmu\)g/100 mL) and beer with mango juice (MJ) (67.152 \(\upmu\)g/100 mL). The smallest amount of \(\upbeta\)-myrcene was recorded in BC (51.683 \(\upmu\)g/100 mL). It is worth noting that, despite the lowest content of volatile compounds in total, the concentration of several components is higher in the BC than in any of the tested beers with the addition of mango fruit. The highest concentration of 3-methyl-1-butanol was recorded in BC (223.169 \(\upmu\)g/100 mL), while the lowest was noted for MJ (177.716 \(\upmu\)g/100 mL). It is one of the higher alcohols (also known as fused alcohols) produced by yeast, which can, depending on the concentration, have both a positive and negative impact on the flavor and aroma of beer [20]. Another compound, the concentration of which was highest in BC (216.684 \(\upmu\)g/100 mL), was phenylethyl alcohol. It is a substance that can be produced by yeast from amino acid L-phenylalanine. It is characterized by a flowery rosy aroma [21]. The lowest concentration was found in MJ (184.237 \(\upmu\)g/100 mL). The total concentration of all volatile compounds in the tested beers was highest for MP (2112.147 \(\upmu\)g/100 mL) and the lowest for BC (1787.836 \(\upmu\)g/100 mL). It is worth noting that an increased concentration of volatile components does not always result in a better beer aroma. The aroma of many chemical substances, such as diacetyl, can be perceived as a defect in beer or some of beer styles. There are also volatile components characterized typically by pleasant aromas, which at a concentration that is too high start to lose their well-perceived fragrances and worsen the beer's acceptability. This is why it is crucial not to only examine the total amount of volatile compounds in beers but to assess how changes in beer brewing technology, such as the addition of fruit, modify the concentration of individual chemicals [22]. Differences that can be seen between the different additions of mango to the beer on the concentration of volatile components can be explained by the way in which mango is processed. MR, MRH, and MHH were characterized by a lower concentration of compounds identified in mango fruit. They were prepared by adding fresh mango preparations. Mango is a climacteric fruit, which means that it can ripen after it is harvested from the tree, in shipping and in storage. It allows for the transportation of fruit overseas, but mango that is harvested after it has achieved its maturity on the tree is characterized by a higher content of volatile components [23]. Mango pulp and mango juice are prepared from freshly harvested fruit and this might be a reason why MF and MJ are characterized by a greater content of volatile components, which come from mango. MJ has a lower content of volatile compounds than MF, because mango juice is essentially mango pulp that has gone through a more effective filtration/pressing process, which could remove particles rich in volatile compounds [24]. Among the beers with the addition of fresh mango (MR, MHH, MRH), MR was characterized by the lowest concentration of volatile compounds. This is probably due to the fact that homogenisation breaks the walls of some mango cells, which releases their content into the solution. Another factor that could explain the higher concentration of volatile compounds in MRH and MHH than in MR is the increased surface contact between particles of fruit and beer, which improves the transfer of acids, phenols, sugars, alcohols, terpen, and vitamins into the beer.