The Art of Wine Making: Choosing Malolactic Conversion or Not for the Wine

Photo by Anastasiia Rozumna on Unsplash

Malolactic conversion, sometime called Malolactic fermentation, is a bacterial transformation (not a fermentation) that can take place in the wine making process. And, wine makers must decide if they want this conversion to occur in their wine.

To get a bit technical, this process allows lactobacilli bacteria to consume malic acid present in the wine, and the by-products are lactic acid, carbon dioxide, and diacetyl. It is this diacetyl that can give a wine (i.e., Chardonnay) a buttery flavor and/or a nutty flavor. This natural process also converts sharper-tasting malic acid (found in green apples) into softer, smoother, creamier lactic acid (found in milk). The process results in the total acidity being reduced, so  the wines become softer, rounder, and more complex. Additionally, malolactic conversion stabilizes wines by preventing an undesirable fermentation in the bottle, often referred to as a secondary fermentation. 

While malolactic conversion is frequently associated with big, rich, buttery Chardonnay, malolactic conversion is not initiated and/or prevented by the wine maker when fresher, crisper styles of wine are desired.

Most red wines undergo malolactic conversion, while only some white wines, notably Chardonnay, undergo malolactic conversion. This process is most often performed shortly after the end of primary fermentation and just prior to the aging process.

So, malolactic conversion is yet another factor that a wine maker must consider as part of the art of wine making. Cheers!

The Top Two Most Prominent Acids in Wine - Tartaric and Malic

Last time we looked at acidity levels in wine that are measured on the pH scale and in terms of grams of acid per liter (Total Acidity). While Total Acidity is a measure of the concentration of acids in a wine, the pH level tells you how intense those acids will be.

So, let’s now look a bit more into the acids in wines.

There are four primary types of acids in wines - tartaric acid, malic acid, citric acid, and lactic acid.

“Wine Diamonds” on a Cork

Tartaric acid is the primary acid in wine grapes. But, only about half the tartaric acid in a grape is soluble in wine. The rest tends to attach itself to pulp debris, tannins, and pigments during the fermentation and aging process. And, sometimes that undissolved tartaric acid crystallizes in the wine. That’s what “wine diamonds” are. Those little broken-glass-looking shards you sometimes find on a cork or in your wine. But, don’t worry, they’re completely harmless.

Now, let’s move on to Malic acid which is the second most prominent type of acid in wine grapes. It too is produced as part of the grape growing process. But, Malic acid in grape vines decreases as vines grow older and the grapes ripen.

If malic acid is too high, winemakers can initiate a process called malolactic “fermentation” (MLF) which converts some of the malic acid (like that of a tart green apple) to the more mild lactic acid. This conversion gives a wine a buttery, creamy mouthfeel. You may know lactic acid as the primary acid present in a lot of fermented products, like yogurt, kefir, and sourdough bread.

Malolactic Fermentation is not actually a fermentation. It’s just a chemical process that converts one type of acid to another type of acid. So, it is more correctly a Malolactic Conversion, not a fermentation.

And, while most red wines undergo malolactic conversion, only some white wines, notably Chardonnay, undergo this process.

If you don’t care for highly acidic flavors in wines, try a full-bodied red wine such as Cabernet Sauvignon, Merlot or a Syrah. But, if you love a crisp, refreshingly tart flavor, look for light-bodied white wines such as Albariño, Sauvignon Blanc, Riesling or a brut sparkling wine.

Malolactic "Fermentation" of Wine - Not

The flavors in wine come from three things - the grapes, fermentation and aging. We've explored the flavors from the juice of the grape, the flavors from the grape skins, seeds and stems and we've seen that the yeast can affect flavors during fermentation. But, there's another process that affects a wine's flavor and it's often called Malolactic Fermentation.

But, getting right to the point, this is not a fermentation. It's actually a process in which one type of acid in the wine is converted to another type of acid. So, it is more correctly a Malolactic Conversion, not a fermentation.

In this conversion process, a tart acid that naturally forms in wine, malic acid, is converted to lactic acid. While the tart malic acid can yield flavor sensations much like a tart green apple, the lactic acid is much softer and creates a richer mouthfeel that is often called buttery and can make a wine seem velvety smooth.

Most red wines undergo malolactic conversion while only some white wines, notably Chardonnay, undergo malolactic conversion. This process is most often performed shortly after the end of primary fermentation and just prior to the aging process.

And, speaking of the aging process, we'll explore the flavors that are imparted to wines as they age in next week's blog. Until then, Cheers!

What are Jammy, Buttery & Earthy Wines?

Ever wonder how terms like 'Jammy,' 'Buttery,' and 'Earthy' can be associated with wine? A product that made with grapes?

Previously we looked at "How do all those flavors get into wine?" There we learned that taste and smell come from the combination of senses from your tongue and your nose that your brain puts together to form flavor. We also learned that aging a wine, especially in oak barrels, can impart flavors that go beyond the fruit flavors from the grape.

So, let's briefly explore the terms 'jammy,' 'buttery,' and 'earthy' with respect to wines.

The first, jammy, is probably the easiest to understand. Just like a jar of fruit jam that you may spread on toast, jammy wines have very concentrated fruit flavors. And because jammy wines are made from very ripe fruit (i.e., high in sugar content) they can end up with just a slight hint of sweetness to go along with the concentrated fruit flavors. Hence, a jammy wine.  Zinfandel is best known for having jammy characteristics.

Next is buttery. Seemly an odd term to be associated with wine. But buttery flavor can be created in wine in one of two ways. First, putting the wine through the process of malolactic conversion (often referred to a malolactic fermentation) turns the naturally formed malic acid that you might associated with tart green apples into lactic acid that is most commonly associated with cream or butter.  The second process that can add buttery flavor to a wine is oak aging.  While most red wines go through malolactic conversion and oak aging, it's Chardonnay that's best known for showing buttery flavors.

Finally, earthy wines are those that have subtle aromas of damp earth, forest floor, mushrooms or a bit of a dusty aroma. Earthy wines include Pinot Noir and Petite Sirah. These should not be pungent aromas, you should just get a hint. If these aromas are strong it usually indicates that the wine has become tainted.

While these descriptors may sound a bit odd when associated with wine, they really can be wonderful enhancements to your wine drinking experience. So, remember to swirl and smell your wines in the glass, then sip. And then see if you can pick out these interesting nuances. Cheers!

Some More Thoughts on Medium and Full Bodied White Wines

Having just examined light bodied white wines and spent a bit of time on Chardonnay, it's time to look into some other white wines that are in the medium body and full body category. These are going to have bigger, fuller flavors than those of the light bodied whites, contain a bit more alcohol and may be aged in oak.

Here are some of the white wines that are considered medium bodied:

Gewürztraminer (go-veertz-tram-ee-ner) - This is a big fruit wine. It's also a very aromatic wine with the fragrance of roses petals, lychee and perfume. Flavors include pink grapefruit, tangerine, peach, mango, apricot and guava. This crisp and fresh flavored wine will typically have sweet undertones while still being dry (low residual sugar). These wines are most famously produced in the Alsace region of France where they can also take on a rich and silky texture with subtle salinity.

Grüner Veltliner (GREW-ner FELT-lee-ner) - Nearly three quarters of all Grüner Veltliner is produced in Austria. This too is a big fruit wine with moderately high acidity. You may find flavors of peach, pear and yellow apple in this wine. The light and zesty versions of this wine are most common and affordable, having crisp acidity and hints of melon and lime. The Austrian Reserve versions can be rich with fruity flavors such as apple, mango and honey along with hints of white pepper.

Sémillon (sem-ee-yawn) - Approximately half of the Sémillon in the world is produced in France with another 25% coming from Australia, and is gaining popularity in California. This is truly a medium bodied wine in all aspects of fruit, acidity and alcohol. Common flavors include lemon, peach, with a waxy mouthfeel and a bit of salinity. Bordeaux blends will include Sémillon along with Sauvignon Blanc. Sémillon is sometimes barrel aged in oak to give it additional richness and flavor.

Marsanne (mar-sohn) - This is a medium-low bodied wine with medium fruit, medium-low acidity but a medium-high alcohol level. Flavors may include Mandarin orange, apricot, and acacia with a slight waxy mouthfeel.

Viognier (vee-own-yay) - This is a big fruit wine with the fragrance of roses, and flavors of peach, mango, and tangerine. Without Malolactic fermentation this wine can also have flavors of lime along with fragrances of flowers and some flavors of mineralality when grown in cool climates. Warmer climate versions of this wine may have flavors of apricot, rose and vanilla. Malolactic fermentation will give this wine richer smoother flavors and reduced acidity.

As previously stated, an oaked Chardonnay is a classic example of either a medium or full bodied white wine, depending on the strength of flavor the oak imparts and if the wine maker takes the additional step of putting the wine through Malolactic Fermentation. And when it comes to full bodied white wines, this is one that everybody knows.

Chardonnay (shar-doe-NAY) - An oaked Chardonnay is a classic example of either a medium or full bodied white wine, depending on the strength of flavor the oak imparts and if the wine maker takes the additional step of putting the wine through Malolactic Fermentation. California Chardonnays of recent past were typically being put through Malolactic Fermentation and aged in new oak to make them a full bodied wine.  These were the Chardonnay's that were referred to as "buttery" due to their big and bold oak flavor and the creamy mouth feel from the conversion of the sharper malic acid (found in green apples) into softer, smoother, creamy lactic acid (found in milk). This process reduces the total acidity such that the wines become softer, rounder and more complex. This trend has largely been reversed such that today most California Chardonnays are either being made un-oaked (often noted on the label), or treated to a lighter dose of oak to allow the fruit flavors to shine through. You can still find a full bodied "buttery" Chardonnay, but they are in the minority.

So there you go with a run through of the various body styles of white wine. Next time we'll start exploring the body of red wines . Tannin is the big difference there. So, until next time, explore some medium and full bodied white wines. Serve them cool, not cold, and enjoy! Cheers!