Racking Off the Gross Lees
Once the alcoholic fermentation has run its course, it’s time for your wine to undergo Malolactic Fermentation, or “MLF” (It’s no coincidence that we’ve also featured an article on Malolactic Fermentationin this month’s newsletter) Before starting MLF, it's important to get rid of the unwanted solids left in the wine after pressing.
A large amount of sediment will settle out of the wine in the first day or so after pressing. This layer is referred to as the lees. What drops out in the first 24 hours is called gross lees, there is nothing beneficial or helpful about them. In fact, the gross lees are often a source of harsh and bitter compounds that, if left in contact with the wine for an extended period, can develop negative sulfur flavors and aromas. To avoid potential problems, we suggest that you transfer the wine off the gross lees between 1 to 2 days after pressing. After this transfer, the resulting wine is often quite clean and will have only a small quantity of light or fine lees (clean yeast, free of solids) that settle out to form a thin layer on the bottom of the vessel. Unlike the gross lees, the light lees are very beneficial to red wine at this stage and will serve as a nutrient source for the Malolactic Fermentation. Once off the gross lees, the wine can safely work in a carboy, tank or barrels for the several weeks needed to complete the MLF.
*Note: It is desirable for red wine to get exposure to oxygen during the first transfer, but only at the first racking. This serves to start rounding the flavors a little sooner. You can do this by simply lifting the transfer tubing up during the racking so that the wine runs down the side of the carboy or tank that you are transferring into. For all other subsequent transfers, you will want to avoid the wine’s contact with air, and to leave the transfer tubing at the bottom of the vessel so it doesn’t splash while you are transferring.
Racking Off the Rest
Having finished MLF, the wine should be removed from any sediment at the bottom of the vessel by racking. Whenever you need to do a racking it is a good idea to test your wine for needed additions (especially SO2). Any addition can easily be added during the transfer. By consolidating multiple tasks into the same winery operation, you can limit the amount of times that the wine comes in contact with oxygen and possible contaminants. In addition, making your addition(s) at the time of a transfer allows the wine to mix itself nicely as it fills the receiving vessel. You can take advantage of this by adding your addition(s) to the bottom of the container before, or in the early stages of the transfer.
Adjusting SO2 Levels
Once the ML fermentation has completed (as verified with Accuvin Malic Acod Test Kit), you need to prepare the wine for the aging/storage. Adding a specific amount of SO2* into the wine and mixing it thoroughly will achieve this. By adding sulfite, we are establishing protection for the wine that will help guard it against oxidative browning and potential spoilage organisms. From this point until bottling, we need to maintain a layer of SO2 protection in the wine at all times.
*The precise amount of SO2 needed is based on the wine’s pH. So, if you will be adjusting the TA /pH of the wine post MLF, keep this in mind when calculating your SO2 addition. A good working method is to add half of the SO2 addition into the wine, test and correct the TA/pH, then add the rest of the SO2 as needed based on the new TA/pH value.
Adjusting the TA & pH
Once the correct SO2 levels have been established, check the TA and pH to see if they need to beadjusted. During the MLF, TA will drop (along with a corresponding rise in pH). Once it stops youwill need to test and taste the wine to see if the drop in acid is acceptable, or if it will need tobe corrected. Red wines should end up in the 3.4-3.65 pH range, but ultimately, your palettewill be your guide. You will use the same guidelines to adjust the wine‟s acidity as you did withthe must, only now you don‟t need to factor out the seeds and skins when making yourcalculations - just use the straight volume of the wine.
Transferring for Long-Term Aging
Once the TA/pH has been adjusted (if needed) and the correct SO2 level has been established inthe wine, we can transfer it to our long-term aging/storage vessel(s). This transfer serves toremove the wine from the combined light and MLF lees, allowing only clean wine to go into thestorage vessels. It's also important to remove nutrients that could be used by spoilage organismsduring the aging/storage period. At this point, all biological activity that we have planned forthe wine‟s existence (primary fermentation with the yeast, and then the secondary fermentationwith the ML bacteria) should be finished. By removing as many nutrients as possible, any spoilageorganism that does make it into the wine has a very hostile environment to survive in. Between the antagonistic effects of the free SO2 and the absence of available food, it should be verydifficult for anything to establish itself and spoil the wine. Removing the lees represents anotherlevel of good winemaking practices that we can utilize to further protect the wine.
If you have used any oak cubes or staves in the primary or secondary fermentations, they willstill have a good amount of life left in them. In order to keep receiving their benefits, just carrythe oak through to the aging/storage vessel. However, they will probably be coated with yeast,bacteria, and tartrates (acid deposits that naturally settle out of the wine over time). You willneed to rinse them off in order to re-expose the wood.
Note: This may require hot water and a sanitized, food-grade brush. Although oak and otherwoods are typically naturally antibacterial, we recommend sanitizing the clean wood with alight SO2 solution (no citric acid) or Star San before returning the wood to the wine.