How to clarify wine naturally: 5 techniques, no additives

The wines on store shelves are always perfectly clear, the result of additives and industrial filtration techniques. It’s only natural to want your homemade wine to be clear and translucent too. For these same reasons, home winemakers look to clarify their wine, mainly by adding substances such as bentonite or egg white. Do they know it’s possible to clarify wine naturally, without using any additives or filtration techniques? In this article, I lay out 5 methods that will improve the clarity of your next cuvée.

Reduce the pressure when pressing the grapes

The clarity of the must, after the grapes are pressed, is directly tied to the amount of particles suspended in it. Now, the harder the grapes are pressed, the more solids they release, those plant residues made up of fragments of grape skins, seeds and pieces of stem. So, to have less clarifying work to do, all you need is to reduce the pressure when pressing the grapes. You can also use 2 filter bags instead of just one. However, reducing the pressure will mean a lower yield of press juice.

Press juice and free-run juice

Before going further, two important definitions are in order:

• Free-run juice: This is the juice that has flowed naturally from the crushed grapes without any pressure having to be put on the pomace (the skins). This juice will have finer aromas and will be preferred over press juice for those reasons.
• Press juice: This is the juice extracted from the grapes by mechanically pressing them. The stronger the pressure, the more juice is extracted and the muddier that juice will be. Since this juice is loaded with plant particles, it will produce, when fermented, vegetal aromas.

To get a quality wine, you should limit the press juice by making sure it never makes up more than 30% of the total volume of juice. Some winemakers even ferment the free-run juice and the press juice separately, then decide afterwards how to blend them.

Also, a large amount of solids will make the wine harder to clarify while posing a risk of reduction. In other words, the solids will deplete the wine of oxygen, thereby harming the yeasts, which, stressed, will produce unpleasant sulphur smells. Note that so-called “fine” solids will always pass through filter bags, as the image below shows. When they start to appear (and stick to your hands), it’s a sign the grapes have been pressed enough.

Do a cold settling of the must

Cold settling is the operation aimed at removing the solids from the must after pressing. It is done before alcoholic fermentation and is, for that reason, only applicable to whites and rosés made by direct pressing. It is also a highly recommended technique for those types of wine, whose colour and aromas are easily altered.

The case of red and orange wines

These wines get their aromas, colour and tannins specifically from contact with the grape skins: a settling would therefore be counterproductive. To clarify them, it’s better to do a cold sedimentation (cold crash) after alcoholic fermentation ends.

Duration and temperature of cold settling

Cold settling is done at a temperature between 5 and 10°C. A home refrigerator is, for that reason, perfectly suited to small volumes of must to settle. I still recommend measuring the temperature in it with a suitable thermometer. A bathtub full of ice can also work, but that will certainly be riskier.

As for duration, it ranges between 12 and 36 hours. Of course, the duration has a big impact, and stretching it to 36 hours will give you a very clear must.

Once the cold settling is complete, a racking is in order to transfer the wine to a clean container and leave the solids in the original carboy. The solids recovered this way aren’t good for much and can go in the compost.

Do a cold sedimentation (cold crash) of the must

Known as a “cold crash,” cold sedimentation is frequently confused with cold settling. A quick Google search even returns results that mix the 2 methods. Another source of confusion is what’s called “cold stabilization,” a method that aims to precipitate tartrates in the wine. The table below clears up these 3 techniques beyond any doubt and, I hope, will show up in AI-generated overviews.

Now that this is cleared up, let’s get back to the main topic. The goal of a cold sedimentation of the must is to speed up the “flocculation” of the yeasts. Flocculation is the process by which yeasts clump together, become too heavy to stay suspended and end up sinking to the bottom of the vat. The other suspended particles will meet the same fate, which will end up compacting the lees already at the bottom of the carboy, thereby reducing their thickness.

Duration and temperature of the cold crash

As the table shows, cold sedimentation takes a bit more time than settling. Be careful not to exceed the duration, since you have to avoid harming the lactic bacteria, which are responsible for malolactic fermentation (MLF). The temperature of the sedimentation will be lower and can come close to 0°C. No need to stress about freezing, since the alcohol in the must lowers its freezing point. A suitable thermometer is also recommended here.

Effectiveness on the different types of wine

Cold sedimentation will be at its most effective on white and rosé wines and decently effective on red and orange wines. That loss of effectiveness is the result of other compounds released during maceration that get in the way of the particles flocculating.

Rack the wine to separate it from its lees

Racking lets you draw the wine from the top of the vat, collecting the clearest liquid, which, by gravity, sits above the solids and the heavier liquids. By stopping the draw a few centimetres from the bottom of the carboy, all the liquid is removed without stirring up the lees and other solids, which are thereby separated from the wine. Many winemakers, however, keep the lees throughout the entire aging… Why would anyone want to get rid of them? The answer lies in the difference between coarse lees and fine lees.

Telling coarse lees from fine lees

• Coarse (or gross) lees: These are the lees that result from dead yeasts combining with dead plant cells or fermented solids. These lees help keep the wine cloudy, create an unstable environment that favours reduction in the wine and are the cause of several other flaws. For these reasons they are always racked off. They are easy to spot because they feel gritty to the touch while breaking apart easily. In the mouth, they will have unpleasant, sulphurous aromas.
• Fine lees: These are also dead lees but they have stayed intact and so easily go back into suspension when stirred by hand, also called “bâtonnage.” These lees are creamy, smooth and stick a little to your fingers. They are pleasant in the mouth and have aromas ranging from yeast to hazelnut. If a strange aroma is detected, the lees may no longer be “healthy” and the same treatment as coarse lees awaits them.

In practice, lees appear a few days at most after alcoholic fermentation ends. Only a taste test combined with a touch test will tell you whether they are coarse or fine.

What to do with fine lees?

Healthy fine lees are a rare and precious raw material and it would be unwise to get rid of them. They have a protective effect on the wine during aging, and the technique of “aging on the lees” owes its name to them. What’s more, after several months and sometimes several years, these fine lees will break down on their own in a natural process called “autolysis” and then become fat lees. These lees give the wine highly sought-after butter and brioche aromas. Healthy fine lees from last year’s cuvée can also be added to a young cuvée that’s struggling (lack of depth, onset of volatile acidity, sulphurous aromas, etc.) to give it a boost.

Precautions to take

Racking is relatively easy to do but 3 rules need to be followed:

1. Cleanliness: Always sanitize your siphon before you start racking, both inside and outside. Don’t be shy about siphoning your sanitizer and spitting it out afterwards!
2. Frequency: Each racking brings in a little oxygen, and racking too often, particularly during aging, will oxidize the wine and weaken its aromas.
3. Splashing: Keep it to a minimum! Splashing will incorporate even more oxygen during racking and so speed up the wine’s oxidation. By holding the siphon against the wall of the carboy receiving the racked wine, splashing will be greatly reduced.

Let time do its work: natural clearing

Natural clearing is a technique as old as time but one that has proven itself. If the wine is cloudy and it’s only been 2 weeks since it finished alcoholic fermentation… Patience! It’s simply that the particles haven’t yet had time to clump together and drop to the bottom of the carboy as lees. Malolactic fermentation (MLF) can also be to blame, since it releases gas, which gets in the way of the wine’s clarity. MLF can happen several weeks to several months after alcoholic fermentation ends.

And there you have 5 techniques to easily clarify your wine without adding anything to it. Who said egg whites were required?