When winemakers speak of racking, they are using a shorthand term for the process by which they siphon their wine into a different container in order to separate the wine from its sediment.
Racking can occur up to four times during a batch's fermentation process for certain red wines. The sediment must be removed from the batch because its presence can cause off-flavors to develop and disturb the fragile taste balance in the wine.
Residue from fruit and yeast, prior to racking. The sediment that collects at the bottom of a fermenting wine's container is usually a mix of dead yeast cells and pulpy residue from any fruit that was used in the mix. Besides being visually unappealing, this sediment can affect fermentation in extremely negative ways. Massive quantities of yeast are used in wine production, and in the presence of either oxygen or sugar, yeast cells multiply , through a process called budding, to up to to times their original number.
In wine production, these chemical reactions produce an output of carbon dioxide and ethanol alcohol. That means at the end of the fermentation process, when the liquid's sugars have all been converted to ethanol, there are still large quantities of yeast particles in the wine that want to react with another particle.
If the sediment is not removed, the active yeast will actually begin reacting with the dead yeast cells. A few weeks worth of these chemical reactions can ruin an entire batch of white wine especially by creating metallic or plastic notes in the bouquet.
Wine racking is more of an art than an exact science, and many experienced vintners have conflicting views on when different wines should be racked. The second racking should occur when the lees pile up to an uncomfortable level once again. Over one inch thick is an urgent concern. Sometimes the lees can ride up the sides of a carboy and look a lot thicker than they really are. Give it a little swirl to agitate the lees every once in a while to get a better read on the situation.
For a red wine, this second racking should ideally occur after malolactic fermentation has completed. If the lees get to a slightly uncomfortable level before malolactic fermentation has completed, give them a swirl about once or twice a week but don't rack yet.
Once you are done with malolactic fermentation and the lees have begun to pile up again, then it is time to rack the wine and dose it with some SO2 to get through the upcoming aging period.
If you plan to cold stabilize the wine, it is ideal to do it right before this racking. Once racked, this is a good time to add any oak products like cubes, staves, or spirals. If you really don't have a whole lot of lees after malolactic fermentation, then you don't necessarily need to rack. At this point, the wine should be topped up and sulfited to prevent malolactic fermentation unless you want that buttery taste like in a Chardonnay.
The third and final racking should occur at the time of bottling. Three rackings usually does the job. At this stage, the wine should have no visible haze and no off smells.
This racking is generally a two stage racking for me. I will rack the wine off of the remaining lees into a temporary blending vessel, like a bucket or carboy. If you have access to inert gas, like argon, go ahead and blanket the storage vessel with gas before transferring to minimize oxygen contact. Any final blending also occurs at this stage.
Sulfites are checked and adjusted at this stage. If making an off dry white or rose wine, I will perform the sweetening and stabilizing now. For instance, if you ferment a white wine at cool temperatures your total fermentation time can extend for several months.
The second racking is done when fermentation has wrapped up. Either an oak barrel or carboy. When this racking takes place depends entirely upon when fermentation ends. This could be a week or up to two months after your first racking. Letting your wine sit on the fine lees for more than two months can lead to flavor and aroma contributions from the decaying yeast. This is known as sur lie aging. It's all part of the job. Don't worry about trying to skim right over the top of the sediment and get all the wine possible out and remove all the sediment.
If you're making wine yourself, there's going to be a small amount of sediment left at the end. Cap the newly filled carboy with an airlock. Once you've gotten the wine in the new vessel, install the airlock on top, which should usually be screwed on securely and then clamped down. Different airlocks will work differently, so it's important to follow the specific manufacturer's instructions.
Most of them will just need to be plugged directly into the opening in the carboy. Part 2. Rack your wine any time it needs to move. In general, winemakers will use the racking process to rack when moving it from the primary fermenter to the secondary vessel, and when moving wine from the secondary fermenter to a bulk aging vessel.
Wine is often also racked after fermentation is complete, to help clarify the wine and remove some of the sediment. The process and vigorousness of racking largely will depend on the variety of wine you're making and your own personal taste as an enjoyer of wine. Do the first racking after days. By the time the batch has been fermenting for a week, it'll need to be put into a carboy with an airlock, which means you'll need to move it from the first vessel anyway, making it a good time to rack it and move it to an appropriate secondary fermentation vessel, outfitted with an airlock.
Be very careful not to rack your wine too early. The fermentation process produces a large quantity of gas, making it dangerous for carboys and barrels alike, if it's too active. For the most part, carboys are made safe by outfitting them with an airlock, which serves to let gasses escape the vessel, but keep outside oxygen, microbes, and bacteria from getting in. Rack when fermentation is completed. The second racking comes when the wine is finished fermenting, sometimes after a few days more and sometimes after as much as a month.
Typically, this racking needs to be done to remove as much of the spent yeast as possible, since it should have settled thoroughly and is no longer affecting the fermentation process. The less sediment that makes it through this first step, the better.
Even this early in the process, as much as 80 percent of the sediment will already be in place, as well as lingering pulp from the must. Rack the wine once more. Most wine is racked no more and no less than three times.
The third racking should be completed when the wine is completely cleared up, and this last racking should be done primarily to remove sediment and clarify the wine. Some winemakers might choose to rack wine again, if the finished product needs to be very clean and clear to satisfy the style and the variety.
Some winemakers will rack several more times to get the clearest wine possible. If you're adding sulfites or are planning to filter the wine before you bottle it, you don't need to rack it anymore. Don't rack every wine. Chardonnay, Champagne, and Muscadet are traditionally bottled on the lee, which some winemakers think helps to alter and integrate the inherent oakiness of the wine.
If you're making white wine and want to try bottling on the lee, you need to taste the batch often and bottle most of it when it tastes right to avoid spoilage. Err on the side of fewer rackings. Every time you rack wine, you expose it to lots and lots of oxygen, accelerating the aging process and exposing it to microorganisms and bacteria.
Since the sanitization process is a long process prone to human error, it's better to put the wine through fewer racking. Less is more.
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