Understanding Wine Acidity: Types and How It Shapes Taste & Smell

1. What Is Acidity in Wine?

Wine gets its bright, fresh flavor from acids. These acids aren’t just one thing-they come in several types that each play a different role in how wine tastes and smells. Some add mouthwatering crispness, while others can create funky or vinegary notes.

There are two main categories of acids:

• Fixed acids (like tartaric and malic) stay in the wine and affect taste and mouthfeel.
• Volatile acids (like acetic acid) can evaporate and influence aroma.

According to research from the University of California, Davis and the Australian Wine Research Institute (AWRI), these acids work together to give wine its structure, lift, and complexity.

2. Fixed Acids: What They Do in the Glass

🍏 Tartaric Acid

• Most stable acid found in grapes.
• Adds sharpness and freshness.
• Keeps wine’s pH (pH is a measurement of acidity or alkalinity) in check and helps preserve it naturally.

🍎 Malic Acid

• Think green apples-it brings a tart, juicy edge.
• More prominent in cool-climate wines and early-harvest grapes.
• Often softened through malolactic fermentation.

🧈 Lactic Acid

• Produced during malolactic fermentation (MLF).
• Adds creaminess and roundness-common in Chardonnay and red wines.
• Brings buttery, nutty, or yogurt-y aromas depending on bacteria strain and wine style.

🍋 Other Acids

Citric, succinic, and oxalic acids appear in small amounts and contribute sourness, umami, or salt-like complexity.

3. Volatile Acidity: Balancing Act

Volatile acidity (VA) refers mainly to acetic acid (think vinegar), and ethyl acetate (smells like nail polish remover).

• Acceptable levels: ~0.3–0.6 grams/liter (depending on style)
• Fault threshold: ~0.7–0.9 grams/liter
• Produced by: yeasts, lactic acid bacteria, and Acetobacter-especially when oxygen is present

Even "clean" wines produce small amounts of VA. The key is control and balance.

4. Natural Wines & Acidity: Why They Smell Funky or Bright

Low-intervention or natural wines often have a different acidity profile compared to conventional wines.

Why?

• Minimal sulfite use = higher microbial activity
• Wild fermentation = mixed yeast and bacterial populations
• Less filtration = more organic acids left in the bottle
• No acid adjustments = natural expression of terroir and vintage

According to a 2021 peer-reviewed study in Foods (MDPI), spontaneous fermentation in natural winemaking sometimes increases levels of volatile acids, succinic acid, and fermentation esters. These add:

• Funky, sour, or savory aromas
• A mouthwatering or “zingy” palate
• Elevated perceived acidity even when actual acidity is moderate

Some natural wines contain higher VA levels as intended by the winemaker, but remain stable and delicious. Again, it’s all about balance and intention.

What This Means for Taste:

• Wild aromatics: sour cherry, kombucha, cider, balsamic
• Textural lift: slight buzz or tang on the tongue
• Lower sulfites: more vivid acidity and natural expression

Not all natural wines are funky-but many showcase the very desired and unique acidity-driven vibrance, it's one of the reasons natural wines feel so alive and full of energy.

5. How Acidity Shapes Your Wine Experience