Originally from the December 2017 Newsletter
What is malolactic fermentation?
Commonly referred to as ML or malo, malolactic fermentation is the process responsible for softer, rounder wines and much of the buttery flavor you may be familiar with in white wines like Chardonnay.
Fun fact: Diacetyl, a compound produced by ML, is responsible for much of the buttery flavor in wine AND the flavor of microwave popcorn!
When asked about ML in the tasting room, my response always begins with the same example. Think of the tartness you taste in a salt & vinegar chip. Rhubarb. Underripe apple. That’s malic acid.
Now imagine you’re eating tangy yogurt or a wonderful piece of sourdough. That’s lactic acid.
Malolactic fermentation is carried out not by yeast, but by bacteria. Their role is to convert that sharp malic acid into a softer, tangy-er lactic acid. This process also gives wines more heft on the palate due to the change in pH and additional byproducts created by the process. In the end, we’re left with a less sharp, more velvety wine. Sounds good? Good.
Shh… Listen…
Each year we use a technique called chromatography testing to ensure that the bacteria have finished their job. It involves lots of dabbing paper with pipettes, very exciting stuff. The more interesting tidbit is that the better way of knowing that ML has finished entirely is to use your ear. By pressing your ear to the opening of a barrel, you can hear work happening! The conversion produces CO2 and, at its peak, sounds almost identical to a crackling bowl of rice krispies. Over time, the crackles slow to an occasional pop, and then silence.
Does all wine undergo ML?
Nope! Most red wines are put through ML, but only specific varietals and styles of white wine are. This process can soften wines that would otherwise be too tart, but others are better suited for a lighter body and higher acidity.
For example, all of River’s Edge’s red wines and most of our whites go through ML, but our Sauvignon Blanc and Gewurztraminer do not. Our Aligoté, usually produced as a fairly acidic wine, is softened by ML to give it a buttery flavor reminiscent of chardonnay. Our Pinot Gris also benefits from the softening effects of ML.
Whew, that was quite a bit of information. How about a glass of wine?
-Colin