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 into 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.
Adjust SO2 Levels
Once the ML fermentation has completed (as verified with Chromotography), 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.
Adjust TA and pH If Needed
Once the correct SO2 levels have been established, check the TA and pH to see if they need to be adjusted. During the MLF, TA will drop (along with a corresponding rise in pH). Once it stops you will need to test and taste the wine to see if the drop in acid is acceptable, or if it will need to be corrected. Red wines should end up in the 3.4-3.65 pH range, but ultimately, your palette will be your guide. You will use the same guidelines to adjust the wine‟s acidity as you did with the must, only now you don‟t need to factor out the seeds and skins when making your calculations - just use the straight volume of the wine. For a review of adding acid to adjust the TA and pH,
For additional information see our Guide to Testing Wine Must.
Transfer Wine to a Long-Term Aging /Storage Vessel
Once the TA/pH has been adjusted (if needed) and the correct SO2 level has been established in the wine, we can transfer it to our long-term aging/storage vessel(s). This transfer serves to remove the wine from the combined light and MLF lees, allowing only clean wine to go into the storage vessels. It's also important to remove nutrients that could be used by spoilage organisms during the aging/storage period. At this point, all biological activity that we have planned for the wine‟s existence (primary fermentation with the yeast, and then the secondary fermentation with the ML bacteria) should be finished. By removing as many nutrients as possible, any spoilage organism 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 very difficult for anything to establish itself and spoil the wine. Removing the lees represents another level 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 will still have a good amount of life left in them. In order to keep receiving their benefits, just carry the oak through to the aging/storage vessel. However, they will probably be coated with yeast, bacteria, and tartartes (acid deposits that naturally settle out of the wine over time). You will need 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 other woods are typically naturally antibacterial, we recommend sanitizing the clean wood with a light SO2 solution (no citric acid) or StarSan before returning the wood to the wine.
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