acidity

I am attempting to distinquish the acids in wine tastings. Could someone help with the description/tastes of malic, citric, tartaric and succinic acids in wine? Thanks.

While I can't give you a lot of info, grapes are perhaps the only fruit that produces tartaric. If you would like to taste tartaric, go to your spice rack, grab that little jar of cream of tartar, mix a little bit up in some water. The dominant acid in most other fruits, apples for instance, is malic. Think sour apple, think malic. Another acid present in many wines is lactic. This is produced by a bacterial fermentation which converts malic acid into lactic acid, which is a weaker acid than malic. When this takes place, the wines have less acidity and a resulting smoother finish. Think lactic, think milk or butter or dairy products. There is very little citric acid in wines, but here, think citrus - limes, lemons - the sourness in the mouth, not the aroma.

Malic acid is what gives the aroma and tartness to green apples. It is perceived on the palate as several times more sour than lactic acid. Red wines tasted from barrel before going through malolactic fermentation are very tart and taste somewhat of apples.

-Paul W.

What is the effect on pH after malolactic fermentation?

Malic may be sharper than Lactic but is it any less acidic?

What is the effect on pH after malolactic fermentation?

Malic may be sharper than Lactic but is it any less acidic?

ML raises the pH, and softens the mouthfeel...gives it that butter quality.

As far as I understand it if the pH prior to MLF is greater than 3.6 the pH will increase during ML. If the pH is less than 3.6 prior to MLF than the pH will decrease during ML. I believe this has something to do with the pKa of the acid and isoelectric point of the acid. (Where's Alan? He could explain this much better than I can).

Salute

I have tasted malic and tartaric acids made up at the same (wine-ish) pH, and they do not have the flavors often attributed to them. In particular, malic acid does not taste like apples. They just taste acidic.

As far as I understand it if the pH prior to MLF is greater than 3.6 the pH will increase during ML. If the pH is less than 3.6 prior to MLF than the pH will decrease during ML. I believe this has something to do with the pKa of the acid and isoelectric point of the acid. (Where's Alan? He could explain this much better than I can).

Salute

Victor,

It isn't safe to do ML above 3.6 pH. I believe the optimum is between 3.2 and 3.5. As for the pH decreasing during ML--I believe that is a rare occurrence.

Try these sites:
http://www.winemakermag.com/departments/112.html
http://www.brsquared.org/wine/Articles/MLF/MLF.htm

The best way to understand the different taste of these acids is to make up some solutions and taste them yourself. Barring that, focusing on the acid profile of apples, lemons, milk etc as people have alluded to here is probably the next best thing. (Of course malic acid doesn't taste of apples, but the predominant acid in apples is malic acid, so focusing on the acid profile of an apple will give you *some* idea.)

BTW, whilst lactic acid is the predominant acid in dairy product, the "buttery" quality in wines is associated with the compound diacetyl. Diacetyl (think artificial butter flavour - like on popcorn) is a metabolic by-product of citric acid metabolisation by ML bacteria. The significant (sensory) presence of diacetyl is not a given with MLF, since its production is dependent on a number of factors.

Sorry Thomas I believe I’m confusing ML for cold stabilization. You’re absolutely correct one should see an increase in pH after MLF.

Salute