The Mysterious “Malo” and What It Does For Wine

Mary Kirk-Bonnet, Sommelier Consel

Reprinted with permission from the French Wine Explorers wine tours

On a recent tour of Champagne, we visited Marie-Noelle Ledru, an independent Champagne producer (recoltant-manipulant) in the Grand Cru village of Ambonnay. As we toured her cellars and she explained her process of making Champagne, she remarked that all of her Champagnes “font leurs malo,” literally translated as “do their malo.” The clients’ puzzled looks told me this needed explanation. They had heard it before, but well ... weren’t exactly sure what it meant. What is this mysterious thing that her Champagne “do?” Today, we’re going to talk a bit about oenology and look at this step of the winemaking process and how it influences the final taste of the wine you are (hopefully) sipping right now!

“Malo” is winemaker’s lingo for malolactic fermentation (also abbreviated in written form as MLF). Wines that “do their malo” are wines that go through a malolactic fermentation. This process takes place right after the primary alcoholic fermentation, when yeasts convert grape sugar into alcohol. In MLF, it is lactic acid bacteria that do the work. These bacteria convert the “tarter” malic acid naturally found in wine (like the one found in green Granny Smith apples), into the softer lactic acid (like the one found in milk). For the MLF to take place, the temperature of the wine must be 68-73° F and levels of sulfur dioxide added to the must after harvest must be low enough to not kill the lactic bacteria. It is important to know that this fermentation step is controlled by the winemakers. They can choose to let it happen or not. The MLF can be blocked by preventative levels of sulfur dioxide or by cooling the wine down to 50° F. These days, some winemakers “inoculate the wine” (add in lactic bacteria) to ensure that the MLF takes place.

Why have wines do their malo? The main reason is to reduce the acidity level of the wine. For grapes that are very tart, MLF gives the winemaker the possibility of producing a more balanced wine. Wines that have gone through MLF are also smoother, with more “roundness” in the mouth.

Most red wines go through MLF. The astringent nature of tannins is more pronounced in the presence of the unconverted, harsher malic acid, but it is tempered when combined with the smoother lactic acid. In this way, MLF helps create a softer, mellower sensation on the palate. Wines that have gone through MLF are also more stable than those that have not. Wines can “do their malo” in the bottle if they haven’t already done it in the winemaking process. It is a rare occurrence, but if you perceive unpleasant fermenting aromas with a slight prickling on the tongue (caused by carbon dioxide, a byproduct of MLF), then chances are that lactic bacteria were still present and a little MLF took place in the bottle.

Okay, but what about white wines? To do malo or not do malo, that is the question! Generally, white grapes that are grown in cooler, northern wine producing regions have higher acidity levels. Winemakers from these regions are more apt to let their wines go through MLF. Burgundy whites, for example, mostly all do their malo. Grapes used to make white wines in warmer, southern regions of France like Bordeaux or the Languedoc already have low acidity. In these regions, winemakers tend to block MLF in order to preserve the tart malic acid and bring needed freshness and vivacity to the wine. It is not that simple though. From my experience talking to vignerons from both the Loire and Champagne regions, I’ve learned that some prefer to let their wines do their malo, some don’t. When tasting Champagnes, for example, I have come across a wide range of acidity levels from very nervous to refreshingly smooth. It depends on the style of wine that the winemaker likes and wants to produce.

In addition to changing acidity, MLF can also modify the aromas and taste of white wines. The milky, buttery aroma and taste you can find in some New World Chardonnays is produced by diacetyl, a byproduce of MLF. Winemakers who want this aroma in their wine will allow MLF to take place. On the other hand, winemakers who prefer a fruitier, crisper style will block MLF because they feel that the resulting lactic acid aromas dominate the more subtle, youthful fruit aromas. Certain aromatic grapes such as Riesling and Sauvignon Blanc generally do not benefit from MLF as it causes them to lose their very distinctive and refreshing varietal aromas. Chardonnay, on the other hand, is a grape that can gain in complexity and body when it undergoes MLF.

To sum up, MLF is an optional winemaking step. The main effects of MLF are reduced acidity and mellower wines. A number of factors including acidity levels at harvest, grape variety and desired wine style all play a role as to whether the wine will be allowed to “do its malo” or not. Armed with this information, during your next visit to a winery, you can drop the question, “So ... do your white wines do their malo?” I’m sure you will impress!