Fining is a winemaking process that is commonly – but not always – implemented. Wine fining involves stirring an adsorbent substance, called a coagulant, into the wine when it lies in barrel or tank, for the purpose of adhering to and removing certain undesirable molecules. This is done to clarify and stabilize the wine before bottling since most consumers prefer wines that are neither cloudy nor excessively tannic.
Wine fining agents fall into one of two basic types, inorganic and organic. The latter include liquids derived from animal by-products like egg whites, casein (a milk protein), gelatin (typically derived from skin, tendon, and muscle), and isinglass (made from air bladders in fish). The most common inorganic example is bentonite, a type of clay. What these substances have in common is a strong ability to adhere to any particles that may contribute to haziness or instability, pulling them out of the wine and depositing them on the bottom of the vessel. When the wine is racked off for aging or bottling, those deposits stay behind. So no worries – there will be no fish bladder in your wine!
As mentioned, not all wines go through the fining process. While quite common in inexpensive wines, the technique is not always used in prestige bottles, since some winemakers believe that it may detract from a wine’s complexity. This is especially true with red wines and has become a widely held belief in California wines, where the phrase “unfined and unfiltered” appears on scores of premium wine labels. Keep in mind that over time, especially with proper aging, particulate matter will naturally settle to the bottom of these bottles, often producing visible sediment. With most white wines, fining still remains a typical process, since consumers tend not to purchase cloudy whites.
It is worth noting that other objections to fining do exist. Natural wine proponents prefer minimal intervention in winemaking and therefore gravitate to unfined and unfiltered wine. Vegans and vegetarians also have their concerns, given that many fining agents are animal-based, as mentioned above. Even though these substances do not make their way into the final, bottled wine, their use at any stage in winemaking can be off-putting for some. For this reason, many producers are moving from such agents to mineral options like bentonite.
Finally, we must add that the use or avoidance of fining does not necessarily equate to quality. An abundance of wonderful wines can be found on both sides of the debate.