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.

Did You Know Cream of Tartar Comes from the Winemaking Process?

You may be familiar with Cream of Tartar. It’s commonly added to egg whites for meringue, it adds loft to baked goods and helps to make fluffier whipped cream. But, did you that Cream of Tartar is a natural by-product of the wine making process?

It comes from tartaric acid, a naturally occurring substance in grapes. During fermentation, the tartaric acid will form in wine making vessels and line the inside with a white sediment. The sediment is removed and ground into a fine white powder, which we know as Cream of Tartar.

Cream of Tartar is also known as Potassium Bitartrate or Potassium Acid Tartrate.

Tartrates are known in the wine industry as “wine diamonds.” Not only do they form in wine making vessels, but they can also appear inside a wine bottle or attach to the inside of the wine’s cork.

These tiny, crystalline deposits are completely harmless. But, winemakers use a process called cold stabilization to remove tartrates from wine before it’s bottled. It’s most is common for white wines to be cold stabilized because consumers commonly store white wines at colder temperatures, which increases the risk for these ‘wine diamonds’ to form in the bottle. Cold stabilization is done mostly for aesthetic reasons so that consumers doesn’t have to deal with the ‘diamonds.’

If you do find these ‘wine diamonds’ on the cork you can simply wipe them away with a cloth. Or, if you see this sediment in the bottle, you can simply decant it to leave the crystals behind. But, either way, don’t worry about seeing these crystals - they are harmless. And, very useful in baking! Cheers!

Ever Wonder What Those Tiny Crystals are on the Bottom of the Wine Cork?

In a recent blog, I wrote about sediment in wine. Those are the particle that are left in your wine glass or inside the wine bottle from tiny particles of grape skins, seeds and stems that are a natural part of wine making. And, other than being an unexpected texture in your mouth, they are harmless.

But then I recently pulled the cork on a really nice bottle of wine that had been laying on its side in my wine refrigerator for little over a year. Upon examination I found a bunch of sparkly red crystals on the bottom of the cork (photo). It was obvious this wasn’t sediment because it had defined crystalline structure. So then, what is it?

Well, without getting too much into the chemistry (and there’s a lot of chemistry in wine making), these are indeed crystals that are sometime referred to as “wine diamonds.”

These crystals are formed in a bottle of wine due to the presence of tartaric acid which, along with malic acid and citric acid, naturally appear in wine. Again, all these little crystals are harmless but the crunch you’d experience in your mouth would certainly be unexpected from a glass of wine.

These crystals can form in both white wine and red wine. While some wine makers will put their wine through additional processing (e.g., cold stabilization) for a few weeks to force these crystals to form and drop out, other wine makers prefer to do as little additional processing as possible to their wines which can result in some crystal formation.

So, if you happen to see these little “wine diamonds” either on your cork or in your glass, don’t be concerned. This is a normal and natural phenomenon. Your wine is just fine! Cheers!