Making wine sustainably and responsibly is not an easy task because it encompasses everything from avoiding conventional pesticides, petroleum-based fertilizers and bio-engineering to abstaining from fining or filtering the wine before bottling.
In winemaking, clarification and stabilization are the processes by which insoluble matter suspended in the wine is removed before bottling. This matter may include dead yeast cells, bacteria, proteins, pectins, various tannins and other phenolic compounds ― as well as pieces of grape skin, pulp and stems. The process may involve fining, filtration, flotation and pasteurization, among others.
During wine production, elements are often introduced to clear the wine, ridding it of cloudiness, bitterness and “off” tastes and aromas. Fining agents tend to work like a magnet, collecting the unwanted constituents that settle to the bottom of the tank. Fining agents include egg albumin, milk proteins, edible gelatin (from bone), and isinglass (from fish), which is concerning to vegans, of course.
Many wineries use the fine clay filter aid kieselguhr, which is a carcinogen, to filter liquids destined for human consumption. The EU-funded project Adfimax is studying a novel vegetable fiber-based alternative which performs better and is sustainable as well.
Fast facts about fining:
- It’s common for quality white, rosé and sparkling wines to use isinglass (a fish byproduct) for fining.
- It’s common for red wines to use egg whites or casein for fining to remove bitter-tasting phenolics.
- Old-world wineries previously used ox-blood to fine wine, but this is no longer common today.
- Fining agents are removed before wine is bottled.
The alternative is to bottle unfined wines. Many experts insist that unfined/unfiltered wines taste fresher, with more purity of fruit, than wines that have gone through the fining process. Natural sediment helps to nourish wine over time, which can help it age gracefully in the cellar.
For the last 25 or so years, wineries have used fining and filtration techniques to make a wine appear crystal-clear. This makes for a more attractive and “trustworthy” product. Most wines sold at retail today are filtered, and as a result you can see right through them (this is most obvious with white wines).
Other more sustainably minded wineries such as Holman Ranch in Carmel Valley, Calif., prefer not to intervene. These wines are often called “natural,” and may leave a bit of sentiment in the bottom of your glass ― a vivid reminder that the wine you’re drinking is the truest expression of a winemaker.