1) Garbage in garbage out! Get the must dialed-in at crush, so that the subsequent wine will be in good shape post alcoholic fermentation for receiving the ML inoculation. A clean, healthy alcoholic fermentation means your ML bacteria will have an easier time getting started and finishing their job when it’s their turn to work in the wine:
2) Post Alcoholic Fermentation:
3) ML inoculation preparation & handling: Prepare the ML culture: Some bacteria are labeled “direct-addition” and can be added to the wine directly from the pouch, while others require a 15–minute hydration period in clean, chlorine-free water before inoculating the wine. However, regardless of these differences all ML bacteria, including the “direct addition” and liquid ones, will benefit from a brief Acti-ML nutrient soak before going into the wine. Therefore we recommend treating any form of ML bacteria you may be working with as if it required a 15–minute hydration before inoculation. This means that: For every 1 gram of bacteria being added to the wine, you will be adding 20g of Acti-ML to 100mL of distilled water at 77°F (25°C). After sitting for 15 minutes gently, yet, thoroughly stir this solution into your wine. The following example will use the 2.5g (66 gallons of wine) size ML bacteria packet to illustrate this.
A) In a sanitized container: dissolve 50g of Acti-ML into 250mL of distilled water at 77°F (25°C).
B) Add the bacteria (2.5g) to the solution and gently stir/swirl to break up any clumps if needed. Wait 15 minutes.
C) Add the entire bacteria/nutrient solution into your wine and mix it throughout the entire wine volume. (Note: it is a good idea to stir the bacteria starter solution just before adding it into the wine to make sure that any of the nutrients and/or bacteria that may have settled-out during the 15 minute soaking period do not get left behind in the hydration vessel).
Inoculation and handling should take care to limit any oxygen exposure (the bacteria are anaerobic and depending on the strain may react negatively to various amounts of oxygen that may be introduced into the wine. In short, don’t splash when stirring the MLF and flush pumps and lines with inert gas before running a wine undergoing MLF through them. In general, it’s recommended not to rack a wine until the MLF is complete, however).
4) During the ML Fermentation:
5) Testing for Completion: Monitor with chromatography* (MT930), and once it seems to be finished, then run the first test. Often a MLF can slow or stop temporarily. If everything in the five elements checks out (alcohol, temperature, pH, SO2, and nutrients) and there is still no more progress within the week, then it’s time to consider adding an ML nutrient (such as Acti-ML) to the wine at a rate of .75–1.0 grams per gallon (possibly with a dose of yeast hulls, as well).
*Note that the sensitivity-threshold for the standard vertical test kit is around 70 mg/l, but it takes around 30 mg/l to be considered truly done. So, a good rule of thumb is to just wait an extra week or two after the test shows that you are done and that should be sufficient for a true completion.
6) Upon completion of the MLF: As soon as the MLF has completed, it is also a good idea to add SO2 immediately in order to stabilize and protect the wine. At this time, the wine should also be re-checked and the pH/TA% adjusted, if needed. If you are working with a red wine, then it is important to rack the wine at this point to counteract any of the reduction that may be remaining from the secondary fermentation. If you are doing a white, however, then you may choose to remain on the lees for more depth and complexity but continue to stir the lees once every 1–2 months.
For additional information on the malolactic fermenation, see our complete Guide to Malolactic Fermentation.
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