Tannins are removed from wine through protein fining, synthetic adsorption, or simply time. The most effective active method is adding a protein-based fining agent, which binds to tannin molecules and pulls them out of solution as sediment you can then rack off. Each approach targets different types of tannins and carries different risks of stripping color or flavor, so choosing the right one depends on your wine and how much correction it needs.
Why Protein Fining Works
Tannins have a natural tendency to bind to proteins. This is actually the same chemistry that creates the drying, astringent sensation in your mouth when you drink a tannic wine: tannins grab onto proteins in your saliva. Fining exploits this by introducing proteins into the wine. The proteins latch onto tannin molecules, form clumps too heavy to stay suspended, and sink to the bottom of the vessel. You then siphon the clear wine off the sediment.
Porcine gelatin is the most commonly used protein fining agent in commercial winemaking because it preferentially removes the large, high-molecular-weight tannins that contribute most to harsh astringency. But different proteins target different tannin sizes. Casein (from milk) is better at pulling out smaller tannin molecules, while gelatin handles the bigger polymeric ones. Knowing this lets you choose a fining agent that matches your problem.
Fining Agents for Home Winemakers
Egg White
Egg white is the classic choice for softening red wines. For a 5-gallon (19-liter) batch, separate one fresh egg and use half the white. Beat it lightly with a pinch of potassium chloride, a splash of wine, and a little water, then stir the mixture into the wine. Let it stand until clarity returns, usually a few days, then rack the wine off the sediment. Egg white is gentle and tends to preserve color better than some alternatives, though it can still reduce color intensity if overused.
Gelatin
Gelatin is the strongest tannin remover available to home winemakers. For 5 gallons, dissolve a quarter ounce (7 grams) in 10 ounces (300 mL) of hot water. Let it stand 10 minutes, stir it into the wine, and rack when clarity returns. Because gelatin is so effective at stripping polymeric tannins, it’s easy to overdo. Start with less than the full dose and taste before adding more.
Casein (Milk)
You can fine with plain milk, which supplies casein protein. Add up to 250 mL directly to a 5-gallon batch and rack after about four days. Casein is particularly effective at removing smaller tannin molecules and works well in white wines where you want to reduce bitterness or browning without dramatically changing the body.
Isinglass
Made from fish swim bladders, isinglass is the gentlest protein fining agent. For 5 gallons, add one tablespoon (15 mL) of granules to two cups (500 mL) of water with half a teaspoon of citric acid, let it stand 30 minutes, then stir it into the wine. Let it settle for two or three days and rack. Isinglass removes less tannin overall but is useful when you want subtle refinement rather than major correction.
Vegan and Plant-Based Options
If you want to avoid animal-derived products, several plant proteins now work as fining agents. Pea protein products (such as Enartis Plantis AF) are the most accessible for home use. For 5 gallons, suspend 2 to 6 grams in ten times as much water, stir the suspension into the wine, let it settle, and rack. Pea and soy proteins remove tannins and reduce astringency at levels comparable to PVPP (a synthetic option), though not quite as aggressively as gelatin.
Potato protein ranks as the second most effective fining agent after gelatin for removing total tannins and phenolics. Rice protein is another strong performer: it showed better clarification ability than gelatin in trials without altering the wine’s composition or sensory profile, making it a lower-risk choice. Grape seed extract has also been shown to significantly reduce astringency in red wines, which is a somewhat counterintuitive result since grape seeds are themselves a tannin source.
PVPP: The Synthetic Route
PVPP (polyvinylpolypyrrolidone) is a synthetic polymer that works differently from protein fining. Rather than binding large tannins, it selectively removes smaller phenolic compounds, the ones responsible for bitterness and browning. It works through hydrogen bonding at its surface, and because of its cross-linked structure, it’s efficient at low doses. International standards allow up to 80 grams per hectoliter. PVPP is especially useful in white wines where you want to prevent oxidative browning, and it can be recovered and reused after sedimentation. It does not remove the larger tannins that cause heavy astringency in reds, so it’s not the best choice if your wine is puckery and dry on the palate.
Micro-Oxygenation: Softening Without Removing
Micro-oxygenation doesn’t physically remove tannins from wine. Instead, it introduces tiny, controlled amounts of oxygen that trigger chemical reactions between tannins and other compounds. The tannins link together into longer chains and bond with color pigments, forming new stable compounds that taste smoother. The result is lower perceived astringency even though the total tannin content hasn’t dropped dramatically. Micro-oxygenated wines also tend to have deeper, more stable color. This technique requires specialized equipment to meter oxygen precisely, which makes it more practical for commercial wineries than home setups.
Aging: The Patience Method
Time alone reduces tannin levels. During bulk aging (in a carboy or barrel) and bottle aging, tannin molecules slowly link together into larger and larger chains. Eventually these chains become too big to stay dissolved and precipitate out as sediment, which is one reason older red wines throw more sediment. Higher storage temperatures accelerate the chemical reactions. In one study, wines stored at 32°C (90°F) showed significantly faster formation of polymeric pigments and faster anthocyanin decline compared to wines at 27°C (81°F). However, that same study found that these temperature-driven changes didn’t noticeably reduce perceived astringency over the 70-day trial period, suggesting that meaningful softening through aging takes considerably longer than a few months.
For home winemakers dealing with a moderately astringent wine, bulk aging for 6 to 12 months before bottling often smooths things out enough without any fining at all. If the wine is aggressively tannic, aging alone may not be sufficient, and fining is the faster, more reliable fix.
Avoiding Over-Fining
The biggest risk with any tannin removal method is stripping too much. Tannins contribute structure, mouthfeel, and aging potential. Remove too many and you’re left with a flat, thin wine. The color damage can be significant too. Bentonite and egg albumin both measurably reduce color intensity in red wines. Gelatin, while excellent at removing tannins, can significantly decrease anthocyanin concentrations (the pigments that give red wine its color). Plant-based fining agents generally have less impact on color and anthocyanin content than their animal-derived counterparts.
Always run a bench trial before fining an entire batch. Take several small measured samples, add different doses of your chosen fining agent, wait for them to settle, then taste. Pick the dose that reduces the astringency you don’t want while preserving the body and color you do. Scale that dose up to your full batch. This five-minute step can save an entire vintage from being stripped into something bland.