This thesis was focused on the effect of ascorbic acid on sensory and analytical parameters of white wine during production technology. The theoretical part is devoted to a detailed description of the mechanisms of oxidation of ascorbic acid and ultimate degradation products of ascorbic acid. In the theoretical part are also given basic methods for the determination of ascorbic acid. Another part focuses on the synergy of ascorbic acid and one of the most important substances in the manufacture of wine, sul-fur dioxide. The practical part includes an attempt was founded in 2014. The study compared different doses of ascorbic acid and sulfur dioxide have been added to the mash two varieties, Riesling and Grüner Veltliner. Attempt monitors antioxidant properties of ascorbic acid and its influence on the analytical and sensory component of the resulting wines. Based on the results, we can conclude that ascorbic acid has antioxidant capabilities asking if it was properly supplemented with sulfur dioxide.

In my thesis, I focused on monitoring of microorganisms in the sample of red grape juice and on the interactions between yeasts, bacteria and filamentous fungi. Three different media were applied for the cultivation of microorganisms; firstly for monitoring of total volume of microorganisms, secondly for yeasts and third time for lactic acid bacteria. The indirect method was used for the determination of the amount of viable cells. This method consists in enumerating of visible macroscopic colonies grown up on agar plates. When the cells grew up, the forms of colonies were analyzed visually and the morphology of microorganisms was detected microscopically. The operating time of enzymes in grape juice in the production of red wine was monitored after application of commercial enzymatic preparation. The enzym action in grape juice was observed on the basis of the process of degradation of high – molecular substrate by enzymes through the use of Ubbelohd´s viscometer. The research findings provided a lot of knowledge about the occurance of microflora in the process of production of red wine. The commercial preparations added to grape juice played a significant role.