NW Winemaking Notes

Cellar Practices:
 from ferment to bottle

When you have decided that your yeast and malolactic fermentations are over, you first sulfite and then begin the processes that will finish the wine for bottling.  Finishing processes (adjustments, clarification, stabilization, maturation) take as little as a couple of months in the case of aromatic whites and as much as two years with full-bodied reds.  The table below indicates (in a broad way) the main finishing techniques you will use. Following the table there is a short discussion of terms and issues, sometimes with links to more technical resources.

Sulfiting

Sulfite (with its SO₂) protects wine from bacteria and oxidation. It is critical to set the right level for your wine initially and then to maintain it through to bottling. You must know the post-fermentation pH of your wine to be able to do this correctly. Ideally, you also know the level of free sulfite at the end of the fermentation. You then consult standard charts that tell you how much sulfite to add to get the level of free sulfite that you need to protect your particular wine.

It is common among home winemakers to be fairly casual about sulfite additions. They may add 30-50 ppm immediately after fermentation and then 15-20 ppm more at each racking and again before bottling. This usually works, but it is easy to end up with too much or too little protection. Even 10 ppm too much can be detectable on tasting and will detract from drinking pleasure. Too little sulfite in white wines (especially sweet ones) or in high-pH reds can lead to bacterial contamination and premature aging.

This is a topic about which it is worth learning a lot more. For a start, see the article by Charles Plant on the BCAWA website.

Aging sur lie

This is done immediately after fermentation when the lees is fresh. Remember that bâttonage (regular stirring) is necessary. For more information, see Ben Rotter's article.

Blending

This is best done as early as possible. Two wines together will have a different chemical makeup than either separately, which means a number of other clarifying and stabilizing processes will work differently in the blended wine. If you blend just before bottling, you risk surprises in the bottle, especially in terms of sedimentation.

Always remember only to blend biologically similar wines—e.g., never blend a wine that has undergone MLF with one that hasn't (unless you have time to wait out more MLF in the carboy or barrel).

Sulfating for reduced sulfur compounds

Use copper sulfate (carefully, of course) whenever you detect a problem, the earlier the better. For more on this topic, see the article by Bill Collings on the BCAWA website.

Back sweetening and sorbating

Whatever method you use to achieve your sweet or semi-sweet wine, you will almost always want to use sorbate to prevent yeast from fermenting the residual sugar.  See the note about sorbate on this website.

Oak treatments and barrel aging

TBD—a big topic and mainly a concern for reds. 

Fining for protein haze

Proteins are an issue in white wines. (In reds, there are more tannins and other phenols, and proteins precipitate in conjunction with these molecules.) If you don't fine a white wine for proteins, you run the risk that these molecules will gradually make longer and longer chains in the bottle. They can form a light, fluffy, stringy sediment that instantly breaks up and swirls into motion when you move the bottle.  This does nothing to enhance the appearance of the wine.  Consumers will usually return a commercial wine with this problem.

Kit wines often fine for proteins by adding bentonite to the juice at the start of the fermentation. This works, but you can also fine for protein later, usually when the wine is already fairly clear from racking. Bentonite is the traditional fining agent, because it has a negative charge to off-set the usual positive charge of proteins.  Bentonite breaks the association of the protein molecules with water, attracts them, and helps them to precipitate.

Many home winemakers today use the Kieselsol/Gelatin fining combination that was developed in Germany for white wines. (Spagnol's supplies a convenient package of the ingredients that is sufficient for one 23L carboy.)  The Kieselsol attracts the proteins and the gelatin helps both to precipitate out.

If you are unsure whether your wine is going to be susceptible to protein haze, heat a sample to 80°C for 30 minutes.  After cooling, look for signs of haziness.  Fining for proteins is sometimes called "hot stabilization."

Fining for Phenols/Tannins

This is a red wine issue.  There is no way to get a red wine to be completely stable in the bottle without stripping it of color and tannins.  Given long enough, almost any full-bodied red wine will throw sediment in the bottle.  The purpose of fining in red wine is to remove the excess or unstable molecules that will precipitate relatively soon in the bottle without any increase in wine quality to justify the mess. 

Phenols and tannins tend to have a negative charge, so the fining must have a positive one.  Gelatin, egg white, and Sparkolloid are typical choices for the home winemaker.

Cold stabilizing

This is usually done when the weather is cold and the wine can be put in a cold place.  Ideally, it is done just before bottling.  Home winemakers often fine with bentonite or Kieselsol/Gelatin just before chilling the wine.  This produces a much more compact sediment when the heavier tartrate settles on top.  For more details see the relevant note and FAQ on this website.

Note: Cold stabilizing your reds before putting them in the barrel could extend the life of your barrel.  Otherwise, you can get tartrate deposits in your barrel (creating a barrier between the oak and the wine) and these are very difficult to remove.

Tannin adjustments

Fining to remove excess tannins is an old practice.  Enhancing tannin during bulk maturation has only come to the fore recently with the availability of products like Tan 'Cor.  Adding tannins during finishing can be combined with tannin enhancements before and during fermentation.  This is a big topic and needs to be explored more in the context of decisions about wine styles and fermentations.  For some more information, see the Scott Labs web site.

Acid adjustments

Most acid adjustments are made before fermentation. After fermentation, it should be more a matter of fine tuning—adding calcium carbonate to reduce acid a little or perhaps adding citric acid to increase it.  See Bill Collings' article about acid adjustment on the BCAWA website.

Filtering

The Club has a filter system which you can borrow. Experts generally agree that filtering is a good thing for almost all your wine, especially when you bottle early (as with whites) and where a bright appearance matters (whites again). 

Bottling

1. Establish an adequate sulfite level a few days before bottling.
2. As much as possible, use the style of bottle that is traditionally associated with the type of wine. In some cases, there is no “typical” bottle, but in many cases there is, and getting a wine into the proper bottle shows that you understand this and care:
• Clear or light yellow bottles for whites. Whites can be in dark bottles, but not the other way around.
• Burgundy-style bottles (the rounder, fatter ones) for Pinot Noir, Chardonnay, and Rhone-style wines (e.g., Syrah).
• Bordeaux-style bottles for Cabernets, Merlot, Sauvignon Blanc.
• The German-style bottle (tall, thin) for Riesling and Gewürztraminer. Bordeaux-style bottles are a second choice for these wines.
3. Clean and rinse bottles with water and invert to drain. You will find bottling much easier if you store your bottles clean, so that they only need to be rinsed quickly at bottling time. DO NOT rinse with sulfite solution. Sulfite is not necessary to sanitize bottles, and rinsing with a sulfite solution will add an unknown amount of sulfite to your wine. Sulfite should be added to the wine prior to bottling.
4. Try to cause minimum disturbance to the wine while bottling, especially if it has been barreled. (White wines that have not been barreled will likely be carrying a fairly high level of dissolved CO₂. Some of this will bubble off in a rush while bottling, which can be an advantage in reducing the “spritzy” character often associated with white wines. However, it it may be better to stir some of this CO₂ out of the wine in the carboy—as instructions for kit wines recommend.

Drafted by Rod Church, for a Club meeting and discussion on February 3, 2004.