This story is over 5 years old.


There's Blood and Bladders in Your Wine

Fining—the process of purifying wine of unwanted tannins, sediment, and colors—is often done with the help of some pretty freaky animal products, like blood, fish bladders, and crustacean exoskeletons. Vegetarians, drink up.

Like any respectable human being, drinking booze is my favorite pastime. When I consider the world of wine, there are a lot of terms that are used to talk about it; fish swim bladder is not one of them. But maybe it should be. Because, lo-and behold, the crystalline clarity of that glass of sauvignon blanc may have the swim bladder of a sturgeon, or any number of bizarre and unexpected fining agents to thank for its alcoholic perfection.


Fining, the process used by a large portion of winemakers to purify and stabilize the wine, gives it clarity of color, removes sediment and suspended solids, and strips away any unwanted tannins, odors, or colors. It's one of the most influential steps on the outcome of the finished product. These fining agents, which are either negatively or positively charged based on what it is the winemaker is trying to extract, are usually added to the barrel or tank after fermentation or before bottling and allowed to sit there, attracting the oppositely charged undesirable particles in the wine, slowly collecting or absorbing them, and bringing them to the bottom, leaving the wine purified.

Depending on what it is you are trying to remove and what type of wine you are making, different fining agents—sometimes multiple ones—are added to the barrel. The weirdest part about all of it is that they're often animal protein by-products, ranging from the mundane (like bentonite, or volcanic clay, and carbon) to the strange and slightly freaky, like casein (milk protein), egg whites, gelatin (taken from pig or cow skin and connective tissue), chitosan (crustacean exoskeletons), kieselsol (colloidal silicic acid), isinglass (fish swim bladder), and even blood. Mmmm, blood.

Isinglass fining solution getting added to a tank of Sémillon. Photo via Wiki Commons.

Isinglass fining solution getting added to a tank of Sémillon. Photo via Wiki Commons.

Fining agents such as isinglass, chitosan, and casein are almost exclusively used for white wines, and egg whites are used towards red wines. Substances like bentonite, gelatin, and kieselsol are more versatile and can be found in white, blush, and red wines alike. But one of the more traditional and effective fining agents has been blood—usually ox—whether in liquid or dried form. Nothing like a little blood to really make a glass of wine sing, amirite?

The use of blood in wine fining is an old practice, one that has dwindled over the years as other means have become available. It's also been banned in the EU and the US since 1997, when the mad cow disease scare was in full effect. France raided several wineries in the Rhône Valley in 1999, confiscating 100,000 bottles that were thought to contain ox blood, as well as 480 pounds of the dried blood fining agent. While some small non-exported Mediterranean wineries may still use blood in the fining process, because of the US and EU's ban on blood as a fining agent, you don't really need to worry about blood in your wine unless you've got a 25-or-over year vintage that you've been saving. And if you do, that's awesome and you should drink it, blood cells or not.

Either way, while some of the agents used in fining are bizarre—and definitely raise questions for those vegetarians and vegans out there—something to keep in mind is that the amount of the fining agents left over in the finished product of the wine is trace, if any at all. Unless you have a severe food allergy to milk or eggs, or an ethical issue with the use of animal protein products, there's no reason not to sit back, relax, and enjoy a vintage glass of fish bladder-fined wine.

This article previously appeared on MUNCHIES in 2014.