Fining is a practice that consists of clarifying the wine following the maturation process, i.e. eliminating certain impurities and suspended elements from the wine in order to avoid cloudiness. Fining ensures colloidal stability and improves the wine's flavour by reducing bitterness and vegetal notes or eliminating oxidized compounds.
After fining, wines appear brighter and clearer. To achieve this, an additive is mixed with the wine to cause flocculation followed by sedimentation of the fining agent and the particles that it carries with it. Various products can be used depending on the particles to be eliminated.
5.4.4 Fining
What container should be used for fining?
Various options are possible:
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Fining in barrels: this is rather time consuming but it avoids having to move the wine and reduces exposure to oxygen, while also enabling the wine to continue to benefit from barrel ageing during the fining process. Fining can take up to 40 days. Fining in a small container also enables faster clarification. Note that a small addition of oxygen prior to fining improves its effectiveness. It is for this reason that fining is usually carried out just after a racking.
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Fining in vats: all the barrels are pumped into a vat and the fining agent is added. The saves a lot of time. However, the wine is handled more since it must be racked and pumped into the vat, fined, then racked from the vat and returned to the barrels. There are therefore more occasions when the wine may be exposed to oxygen and a loss of barrel ageing time while the wine is in the vat.
When is the best time for fining?
Micro-fining can be carried out early in the ageing process to preventively clean an environment that is particularly prone to spoilage microorganism development and has poor filterability (see the bottling section). This practice involves using a very small amount of fining agent early on to initiate a good clarification during ageing. This method is being tested on certain batches that are particularly difficult to clarify.
Otherwise, fining is more commonly carried out at the end of the ageing process, as close as possible to bottling. Wine is more sensitive to oxygen and woody flavours after fining.
A double fining procedure is sometimes carried out in very specific cases, for example with batches of press wine containing a lot of lees and pectin.
What fining agents should be used?
There are many products and the selection of a fining agent will depend on the nature of the elements to be removed from the wine. For example, bentonite is perfect for removing proteins and patatin for tannins.
Moreover, some fining agents such as casein (milk) or albumin (egg) are food allergens, which should be taken into account, although their use does not make the wine allergenic since these products do not remain in the wine.
Here is a non-exhaustive table of different types of fining agents:
| Fining agent type | Origin | Characteristics |
|---|---|---|
| Bentonite | Mineral | Suitable for white wine protein stabilization |
| Albumin (egg) | Animal | Adapted to tannic wines, traditional fining agent used for Bordeaux red wines. |
| Isinglass | Animal | Derived from fish waste such as bones, skins... It gives excellent results for fruity whites and wreakly tannic reds. Helps to lower turbidities. |
| Patatin | Vegetable (potato) | Suitable for all 3 wine types, it can be used to correct wines that are too tannic through its significant coagulative capacity. |
| Pea fining agent | Vegetable | Preferentially used for white or rosé wines because less effective in relation to tannin precipitation. |
How is the appropriate product and dosage determined?
Testing the fining agent type along with dosages for each type is recommended. The objective is to achieve good wine stability (colour, tartaric precipitation, microbiological risk) and an optimal organoleptic profile. Over-fining can be detrimental to the wine. This can lead to further instability, especially if it is exposed to tannins, for example, during barrel ageing. This can lead to cloudiness.
The dose has an impact on the quantity and type of precipitated elements.
Fining using egg whites (Credit: P. Faigenbaum)
For example, certain fining agents can lead to the loss of aromas. Albumin in large quantities, for example, can remove up to 8% of the aromatic compounds.
Consequently, several samples should be taken before the fining period, and several types of fining agents tested in bottles at different doses, followed by a comparative blind tasting. For example, for a trial on egg white fining, seven samples should be taken from each batch to try fining agent at doses ranging from 0 to 6 eggs per barrel.
Sometimes the unfined wine has a better taste profile without fining. Wines can remain unfined if they are stable and without microbiological risk.
At Château Latour, egg white fining is, historically, the fining technique that best matches the wine's rich tannin profile. Nevertheless, tests are carried out every year with other fining agents and compared in blind tastings.