Mastering Malolactic Fermentation

Mastering Malolactic Fermentation

At this time of year, the grapes are in, the ferments are winding down or done and for a good portion of wines, it’s time for malolactic fermentation (MLF). Just like with your primary fermentation, the best results happen when you have the right nutrition and a healthy environment. For those wines where you do not want MLF to happen, it’s also good to know that you can have tools at your disposal to control or prevent MLF.

Bactozym® SG (lysozyme) is one of those great winemaking tools. When making white and red wines, various situations may occur which require controlling the bacterial population without using excessive doses of sulfur dioxide. Bactozym® SG can be used in all situations where you want to reduce counts of gram positive bacteria like Lactobacillus, Pediococcus and Oenococcus or even avoid malolactic fermentation completely. If you are still dealing with stuck ferments, a dose of Bactozym® SG can really help control lactic acid bacteria, therefore limiting the potential negative impacts of increased volatile acidity.

Oenococcus oeni, the bacteria that is responsible for completing MLF, is gram positive, so therefore can be significantly reduced and inhibited by Bactozym® SG. In some situations, it may be desirable to delay malolactic fermentation to lengthen the structuring phase; Bactozym® SG can accomplish this as well. Perhaps you want to make sure your Chardonnay doesn’t go through MLF this year to preserve acidity and freshness, Bactozyme® SG can help. If you want do some extended maceration and you don’t want to go heavy on the sulfur, Bactozym® SG can help. You can ensure a late MLF for structural reasons, adding a low dose of Bactozym® SG early after primary fermentation is completed and then inoculating with a strong clean ML culture (like Amar04 or Oeno) later that. When you find the right balance blending lots where one wine has completed MLF and the other hasn’t, Bactozym® SG can inhibit activity and help stabilize the wine.

 Product detail: Bactozym® 100 g & 500 g


Inoculating with a strong Oenococus oeni strain will go a long way to ensuring success when you are trying to have a healthy, complete malolactic fermentation. For ML fermentation, inoculate with a strong population as soon as possible after primary fermentation complete before racking off fine lees. In some cases, like higher pH (3.5+) and noncompetitive yeast strains, it is possible to add just before primary is finished. This will give as little opportunity as possible for spoilage organisms to take hold before sulfuring.

Vason Amar04® is a direct addition ML culture isolated from Amarone by the University of Verona that produces very low acetic acid. It’s hard to beat for ease of use as well as the high quality organoleptic character and speed of completion. Amar04® has an SO2 tolerance of up to 30-40 ppm total (10 ppm free), a pH tolerance of 3.2 and an alcohol tolerance of 16%.

                  Product detail: Amar04® S (66 gal), M (660 gal) & L (2640 gal)


Oeno™ ML bacteria by Kerry provides a highly concentrated culture of Oenococcus oeni that is very reliable, convenient and cost effective. It has excellent sensory properties for red, white and rosè wines with a pH tolerance of 3.2 and an alcohol tolerance of at least 13% (anecdotally, users report much higher tolerance). One container of Oeno™ is capable of inoculating 500-1,500 gallons of white or rose wines, or 3,000-5,000 gallons of red wine. This product does require bioactivation before adding to wine, but offers an excellent option for inoculating larger volumes of wine at low cost.

Product detail: Kerry Oeno™ Cups 1 cup, case of 12 cups  (price breaks at greater case quantities)


Appropriate nutrient content is important for ML bacteria just like for yeast. Unlike yeast however, bacteria are unable to store nutrients nor are they able to synthesize all necessary amino acids. Therefore, appropriate nutrition must be found in the wine. Nutrient deficiency is a common reason for MLF that starts but doesn’t run to completion. This can be very prevalent when primary fermentation has been completed by a nutrient hoarding yeast strain.

Leucofood® can help ensure a healthy and complete ML fermentation. It is a complex blend of yeast extract, casein digests, vitamins and minerals specifically formulated to provide the appropriate levels of nutrition to Oenococcus oeni. It has no DAP, as bacteria are incapable of using inorganic nitrogen.

Product detail: Leucofood®100 g, 1 kg, 5 kg & 25 kg

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