Fining (with egg-whites)
Fining is about extracting selected chemical compounds from wine. It works by adding a fining agent which binds to that compound and then precipitates so the sediment can be removed by racking. There are two kinds of fining agents: some hold an electrical charge which attracts large particles with the opposite charge, others form a chemical bond with selected large particles. In large commercial wineries fining has become a sophisticated industrial process – quite an evolution from fining with egg-whites practised for over a hundred years.
With the industrialisation of winemaking, we have seen a proliferation of fining agents developed and marketed by speciality chemical companies to adjust wine for a plethora of “faults”.
The table on the right, extracted from the November 2015 Newsletter by Enartis-Vinquery (http://www.enartisvinquiry.com ) highlights a large number of the fining agents they currently suggest for different effects.
Fining has a long tradition, especially in the Bordeaux. There, egg-whites had been used for decades to tame strong tannins, reduce astringency and give the wine a rounder mouthfeel. Recently in Europe, however, regulation has been passed that forces wine-makers to disclose on the bottle label any addition of animal products – e.g. egg whites, while the same disclosure requirement does not apply to industrial fining agents. The consequence is that egg-whites are being replaced by industrially produced albumin which represents the key fining agent in egg-whites.
To date, we have not used any industrially produced fining agents. We have opted for fining with egg-whites only once: to contain the harsh tannins and astringency in the over-extracted 2010 vintage.
Fining with egg-whites
Egg-whites are one of the oldest fining agents. The positively charged peptide linkages of the albumin and globulin proteins form hydrogen bonds with negatively charged hydroxyl groups found in large tannins. Once the two attach, they become neutralised, and the particles settle, due to their heavier weight.
Process: The egg-whites need first to be separated from the egg-yokes. Then the egg-whites (one third) are mixed with a 0.7% salt water solution (two thirds) because globulin is only soluble in salted water. Then the solution is added to the wine and stirred in well. Finally, a week later, the wine is racked.
Timing: The opinions on when to fine vary. Some argue red wines should be fined and racked just before assemblage and bottling; others argue red wines should be fined right after malolactic fermentation is completed. We tried egg-white fining for the first time in spring of 2013 right before bottling on the 2010 vintage. Time will tell.
The optimal Dosage varies anywhere between 1 and 6 egg-whites per barrel. So first we need a test for the optimal dosage. We do this by tasting 1-litre samples of wines at concentrations equivalent to 1, 3 and 5 egg-whites per barrel. We call these samples 1E-wine, 3E-wine and 5E-wine respectively. Because the amount of egg-whites needed for 1 litre is so small, we first create a sample which has a concentration of 22 egg-whites per barrel (22E-wine) and then dilute it down. This is the process we use to prepare the samples:
- Mix 1 egg-white (~32 g) with 65 ml of water with 0.65g of salt and stir well (the “1E-solution”); the total is ~95 g.
- Pour 4.5 g of 1E-solution into 450ml of unfined-wine to get the 22E-wine
- Mix 45ml of 22E-wine with 955 ml of unfined wine to get a 1 l sample of a 1E-wine
- Mix 140 ml of 22E-wine with 860 ml of unfined wine to get a 1 l sample of a 3E-wine
- Mix 240 ml of 22E-wine with 760 ml of unfined wine to get a 1 l sample of a 5E-wine
We then compare the samples daily for 6 consecutive days and select the solution which tastes best.
For more background on fining with egg-whites consult the following links:
- http://www.wineportfolio.com/sectionLearnClarifyingWineWithEggWhites.html start at minute 4.
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Last updated: February 29, 2018