Slovak wine following terms: Víno bez zemepisného označenia - "Wine without geographic indication" is replacing former category of Stolové víno - Table wine. Minimum level of sugar content is 13 °NM. Víno s chráneným zemepisným označením - "Wine with protected geographic indication" - produced from grapes registered in the List of registered varieties, grown, produced and bottled in one of the Slovak wine regions, maximum yield per hectare wasn't exceeded, minimum level of sugar content was 13 °NM and it fulfills the requirements of established product specification. It can be indicated with traditional term regionálne víno if the grapes reached 15 °NM,
Phenolic content in wine grapes varies depending on the variety with Cabernet Sauvignon, Nebbiolo, Syrah and Tannat being 4 of the most tannic grape varieties. The reaction of tannins and anthocyanins with the phenolic compound catechins creates another class of tannins known as pigmented tannins which influence the color of red wine. Commercial preparations of tannins, known as "enological tannins", made from oak wood, grape seed and skin, plant gall, chestnut, quebracho, gambier and myrobalan fruits, can be added at different stages of the wine production to improve color durability. The tannins derived from oak influence are known as "hydrolysable tannins" being created from