Functional beverages are one of the categories within the concept of functional foods. They are the most popular and widely used category of functional foods because of their practicality, ability to meet consumer demand for desirable nutrients and functional components, ease of distribution and the ability to change size, shape and appearance of the packaging. The development of a functional beverage is a complex process, and the functionality of the final product depends on the selection of starting raw materials and ingredients, processing, storage, and delivery methods and the achievement of appropriate sensory characteristics. In this diploma thesis, a functional beverage based on barley malt wort was produced using the Grainfather system. The production technology of the beverage can be divided into two phases, namely the production of the wort (brewing) and the fermentation of the wort by lactic acid bacteria. The functionality of the product results on the one hand from the raw material itself (barley) due to its phytochemicals and on the other hand from the technological (malting) and biological (fermentation) processes. The lactic acid bacteria, used in the production process improve the organoleptic properties, extend the shelf life of the beverage and have a probiotic effect. The beverage produced is characterized by a sour taste due to the low pH value (3,65), resulting from the formation of lactic acid during the fermentation process. Although the GC-MS analysis showed that the volatile aroma substances are predominantly alcohols, such as ethanol and 3-methylbutan-1-ol, the citrus aroma (lemon-like), which is attributed to the compound from the terpene group limonene is most prominent. The functionality of the beverage is achieved through the selection of barley malt as raw material and the fermentation process using lactic acid bacteria, which indirectly affect the functionality of the product by forming various desirable compounds and reducing undesirable ones. The microbiological analysis confirmed that the lactic acid bacteria in this beverage also have direct impact on the functionality as probiotics due to the high number of bacteria (2,2×10 6 CFU/mL).