During the process of alcoholic fermentation, the brewer’s yeast synthesizes, except for ethanol and carbon dioxide, a broad spectrum of various by-products of metabolism and most of them are emitted to the environment. In different types of beer, more than 1000  components can be found including ca. 200 carbonyl compounds. The quantity and quality of products and indirect metabolites emitted from cells impact the organoleptic qualities of finished beer. Besides the components of hop, those compounds give it a specific and  characteristic taste and aroma. Vicinal diketons are one of the groups of those compounds. They are important components of the taste  and aroma of the young beer. In beer, two basic components from the group of diketons are present: diacetyl and 2,3-pentanodion. Their  impact on the taste and aroma is generally negative; however, they are considered to be „determinants of beer maturity”. In higher  concentrations, they give the beer a sweetish, impure and, sometimes, improper taste, and the aroma reminds that of butter. They are  formed from the precursors produced by yeast during fermentation. At the next stage of fermentation, the beer is subject to a process of  maturation the main purpose of which is to decrease the amount of vicinal diketons or to eliminate them. At this stage of the process, the  diacetyl diffuses back to the cytoplasm of yeast cell and, next, is subject to reduction to acetoin as a result of the activity of diacetyl  reductase enzyme. The process of conversion is regulated by the temperature and length of the maturation process with the purpose of  producing beer of a proper taste and aroma. The objective of the research study was to give an outline of formation mechanisms of vicinal  diketons during fermentation of beer wort. Described is the meaning of diketons in the process of beer maturation since their appropriate  quantity is considered as a determinant of completing this stage of the beer production process. Moreover, some selected technological  parameters are depicted the optimization of which ensures that a low content of diacetyl and 2,3-pentanodion in a finished product can be  achieved.