Racking your hard cider simply means to siphon off the cider leaving the bottom layer of sediment behind. To answer the question of when you should rack your cider, I first need to review the definition of sediment and lees. Apple juice contains a variety of organisms and compounds. Many of these precipitate or drop out of the cider and collect in the bottom of the container as sediment. If you let freshly pressed apple juice sit, you can get a sediment layer that is mostly apple pulp or solids, which were left in it from the pressing process. If you treated your pomace or juice with a pectic enzyme, the sediment will include both apple solids and pectin. This sediment will harbor organisms like yeast as well as lactic and acetic acid bacteria. After fermentation, the sediment is often called lees and, lees are usually categorized as gross or fine. Gross lees is the sediment formed once fermentation completes. It includes higher levels of apple solids. Fine lees is the sediment formed after a cider has already been racked at least once. As is common for making hard cider, there is no right answer for when you should rack it. However, there are three times you can rack during cider maker. Let’s explore why you would rack. The three times are racking your juice before fermentation, racking the cider after fermentation is complete, and racking during the aging or maturation process.
Racking Your Juice
Want a fruitier hard cider? You should rack your juice. Juice with fewer solids and other compounds like pectin will ferment slower. That means you will lose fewer aromatic compounds from the vigorous release of CO2. Juice with high amounts of apple solids provide an excellent place for lactic and acetic acidic bacteria to reside and reproduce. It provides them a protected environment where they can produce undesirable (think vinegar and farmyard) aromas. Letting your juice sit overnight, I add pectic enzymes and cold crash mine, and then racking the clear juice off the sediment, will create a juice that ferments less vigorously (you won’t need to keep cleaning out the airlocks) and produces a more aromatic cider that has fruity notes. Racking your juice also reduces the nutrients, making it more likely that you could produce a naturally sweet cider. You don’t have to rack your juice but, if you want a slower fermentation with more fruity aromas and a chance for residual sweetness, you may want to consider it.
Racking Off Gross Lees
After fermentation completes, you should notice that the cider begins to clarify. It becomes less cloudy and you will see a layer of sediment forming on the bottom of the fermenter. This layer is called the gross lees. Gross is referring to the size (large) versus disgusting, though some of it can look disgusting. If you didn’t rack your juice, this can be a rather large layer and it contains lots of different compounds and organisms. If the lactic and acetic acid bacteria haven’t already started to reproduce, this layer of material can give it the nourishment it needs. The solids will contain small amounts of sugars, the dead yeast can release key nutrients and compounds allowing this bacteria and even other yeast, like Brettanomyces, to start becoming active. These organisms usually produce less desirable aromas and compounds. If you racked your juice and you want to encourage processes like malolactic fermentation (MLF), leaving the cider on the gross lees should expedite that process. However, it is usually recommended to rack the cider off these gross lees within 1-2 weeks from the fermentation completing to prevent these organisms from starting become active. Cider will usually still be cloudy at this point but most of the large particles and solids will have precipitated out into the sediment layer. What is left is what will make the fine lees.
Racking Off Fine Lees
Fine lees usually contain mostly yeast. These are organisms that are usually alive and have resisted flocculating and dropping out. With time, they finally do flocculate with other yeast cells or compounds and slowly fall to the bottom of your aging vessels. Your cider becomes clear and you get a smaller or finer layer of sediment in the bottom of the container. These yeast were alive but with time, they can start to die and go through autolysis, providing a nutrient rich layer for mostly lactic acid bacteria to utilize. Acetic acid bacteria requires oxygen so how you are racking and storing your cider (barrels, plastic, corks, stainless, glass) will impact how much oxygen is available for it to become active. However, lactic acid bacteria generally works in an anaerobic environment. If you want to encourage processes like malolactic fermentation (MLF) or evolution of tannins and polyphenols, leaving your cider on the fine lees can aid that process. Racking it off these lees will help prevent those processes from occurring.
As you can see, when to rack your cider, depends on what you are trying to produce. You may want to first rack the juice and rack it after fermentation completes. Finally, you may or may not want to rack your cider while it ages and clarifies. You could also just let the cider sit in the fermenter until you are ready to bottle or drink it. The choice is yours to make but, hopefully, you now understand how those choices may impact your final product.
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