Racking is simply the process of transferring a wine from one container to another while leaving behind any sediment or "lees". Why do you rack your wine? Over time fruit particles and dead yeast cells will settle out of the wine and pile up on the bottom of your container. In the first days after pressing a wine, this layer will be very thick and particularly troublesome. This thick layer of yeast and fruit crud is referred to as the gross lees, whereas the thinner sediment later on is known as the fine lees. The main purpose of racking is to separate the clean wine from these decaying lees to eventually form a crystal clear and ready-to-bottle wine... but the question is... How often should you rack your wine?
Racking Equipment
No crazy equipment needed here. A simple 3/8 inch stainless steel racking cane and some 5/16 inch food grade tubing are my go-to racking equipment. A 5/16" tube will stretch over the 3/8 cane nicely with virtually no risk of falling off or leaking on you. The stainless racking cane will last longer than you and the tubing can be replaced with very little cost. This size is good enough to handle most home winemaking transfers and will go a little faster than the plastic canes due to the thin walls and larger inside diameter. I have a 1/2 inch racking cane, but it is generally a little too aggressive and can really disturb the lees during a racking. Larger canes can be used for larger transfers like barrel to barrel.
What if you don't Rack?
Leaving the wine on a stagnant, thick layer of lees for too long can cause some serious problems with the wine. A pile of angry, unfed yeast cells will generally start creating hydrogen sulfide (rotten egg smell), which can morph into the dreaded organosulfur compound, mercaptan (burnt rubber taste). Any leftover nutrients that may have fallen out of the wine after fermentation can also feed unfriendly bacteria and yeasts. These are obviously not good things...
*Occasionally, some long term lees contact is welcome but on fine lees, not the gross lees. This means, you still need to rack after pressing the wine. If making a kit, you can wait quite a while to rack since you really won't have much for gross lees. The process of stirring the lees (aka Bâtonnage) is commonly used when making wines like Chardonnay and can create a bit more mouth feel.
What if I Rack too Many Times?
Getting a little to ambitious with your racking frequency will generally diminish aromatics to some extent, and often cause full blown oxidation. Each time you rack the wine, a small bit of oxygen will be absorbed which can react with volatile aroma compounds. To scavenge this oxygen and maintain protection against oxidation, 20-40ppm of sulfur dioxide (SO2) are generally added at each racking. This helps to prevent things like VA (Vinegar), nasty aldehydes or ethyl acetate (acetone smell). To prevent these faults, it requires a lot of total SO2 if you rack many times. I have heard a lot of novice winemakers racking five, six, or seven times to "improve" the wine, but usually will do the opposite when done excessively.
When or How Often Should I Rack?
The first racking should occur shortly after pressing the wine.
If it is a red wine, pressing will usually be after the primary fermentation is complete. Let the wine settle out for one or two days, then rack off of the thick layer of gross lees. This is the most critical racking and can be a make-or-break situation for the wine.
If it is a white wine or rose, the first racking will occur after pressing but before fermentation. The gross lees at this point consist mostly of fruit pulp. It is nice to get some of this separated if you can. If you can chill or "cold settle" the juice, it will buy you a bit more time to let the pulp settle out. Get what you can, but you don't need to get too crazy at this point. A little bit of solids can help the fermentation.
The second racking should occur when the lees pile up to an uncomfortable level once again. For me, I consider any lees over about 3/8 of an inch thick to be a little risky for the long haul. 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.
*For a white wine, the second racking is generally after fermentation has completed and things have settled out for about two days. 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. Then it goes right into the bottle.
There are occasionally exceptions that would require another racking at some point along the way. If you want to pull the wine off of the oak, the easiest way is to rack it off. If you are getting some reductive/swampy smells, you may want to splash rack to introduce a little air to the wine. If you are stealing wine for a blend, you may need to downsize to a smaller carboy to reduce head space. You know what they say... when you gotta rack, you gotta rack...
As a general rule, don't rack unless you have a reason to rack. While you are racking, make sure to give the wine a taste and smell to make sure things are going in the right direction. Sanitize your equipment with a no rinse sanitizer like Star San when racking. If you want to minimize oxygen contact, consider blanketing both wines with argon during the racking process. Whenever you transfer to a new container, make sure to top up. You can use a previous vintage of a similar wine, or a store bought wine that is similar. That's about it to the racking process!
For more information be sure to check me out on Youtube at The Home Winemaking Channel.
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