Vegetarianism and wine
Wine is sometimes finished with animal products. Specifically, finings used to remove organic impurities and improve clarity and flavour include several animal products, including casein, albumen, gelatin and isinglass.
Wineries might use animal-derived products as finings. To remove proteins, yeast, and other organic particles which are in suspension during the making of the wine, a fining agent is added to the top of the vat. As it sinks down, the particles adhere to the agent, and are carried out of suspension. None of the fining agent remains in the finished product sold in the bottle, and not all wines are fined.
Examples of animal products used as finings are gelatin, isinglass, chitosan, casein and egg albumen. Bull's blood is also used in some Mediterranean countries but (as a legacy of BSE) is not allowed in the U.S. or the European Union. Kosher wines use isinglass derived from fish bladders, though not from the sturgeon, since the kosher status of this fish is in debate .