Oxidativní enzymy v hroznech révy vinné

The main objective of the Thesis is to understand the oxidation of must, especially enzymatic oxidation. It is caused by the oxidative enzymes that are already present on the grapes in vineyard, especially on those badly infected by mushroom diseases. The two main oxidative enzymes that need to be targeted are tyrosinase and laccase, collectively called polyphenoloxidasi (PPO). These most active oxidative enzymes, which already oxidize the must in the beginning of wine production and degrade the quality of future wine, belong to the group of oxidoreductases where oxygen is a catalyst for enzymatic activity and the phenolic compounds are substrates. Another main goal of the Thesis is to determine polyphenol oxidase activity on several samples of varieties and to compare how it affects other wine parameters such as acids, sugar content, etc. We will discus the oxidation of caftaric acid and its subsequent conversion to quinones. Quinones are just the product of the oxidation of phenolic compounds due to the activity of these enzymes. Caftaric and coutaric acids are the most oxidizable compounds for these enzymes and will therefore be discussed in more detail. It is also necessary to focus on possible protection against enzymatic oxidation