Black grapes The basics of winemaking are covered in every WSET wine course! At WSET Level 1, you'll learn one of the fundamental differences between white and red wine production. For white wine, grapes are typically pressed before fermentation, meaning the juice ferments without the grape skins. For red wine, fermentation takes place before pressing. The grape juice (or must) ferments together with the skins, allowing colour, tannins and flavour compounds to be extracted. T