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HOMEMADE COUNTRY WINES · EST. 2026
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Guide · basics · 4 min read

Testing for Acidity.

Test acidity in homemade wine with confidence. This guide covers why acid balance matters, how to measure it accurately, and how to fix common problems.

Hands using a titration kit to test wine acidity on a walnut surface in warm natural light

Testing for Acidity in Homemade Wine

Acid is the backbone of wine. It controls flavor, balance, and even how well your wine ages. Too little and the wine tastes flat and flabby. Too much and it bites back like a lemon. The good news is that measuring acidity is not a chemistry final — it’s closer to a cooking show experiment, and the math stops at long division. Here’s how to do it right.

Why Acidity Matters

Acid gives wine its brightness and structure. It also acts as a natural preservative, helping protect your wine from spoilage organisms. When winemakers talk about acidity, they usually mean titratable acidity (TA) — a measure of the total amount of acid in your wine or must (the unfermented grape juice and pulp). This is different from pH, which tells you how strong or aggressive an acid is, not how much of it is present. Think of TA like counting how many lemons are in a pitcher of lemonade, while pH tells you how sour each sip actually tastes. For most home winemakers, keeping an eye on TA is the single most useful acidity measurement you can make.

What You Need

You don’t need a laboratory. A basic titration test kit — available at any homebrew or winemaking supply store for under $10 — comes with everything you need:

  • A small, clear sample bottle or glass
  • A phenolphthalein (fee-nawl-THAY-leen) indicator solution — this is a liquid that changes color when the acid in your sample is neutralized
  • A titrant solution, typically sodium hydroxide (also called lye), premixed at a precise concentration
  • A small syringe, usually 10 mL, marked in small increments

That’s it. No beakers, no lab coat, no graduate degree required.

How the Test Works

The process is called titration — adding a measured amount of a known solution to your sample until a chemical reaction is complete, then reading how much you used. Here’s the step-by-step:

  1. Measure your sample. Draw 15 mL of wine or must into your sample container. Use the syringe or a measuring pipette if your kit includes one.
  2. Add the indicator. Drop 3 drops of phenolphthalein into the sample. Nothing dramatic happens yet — that’s normal.
  3. Fill your syringe. Draw the sodium hydroxide titrant up to the 10 mL line.
  4. Add the titrant slowly. Add it a little at a time — roughly half a milliliter per addition — and swirl the sample after each addition.
  5. Watch for the color change. At some point, the sample will shift color. White wines turn pink. Red wines turn grayish (the red pigments in the wine interfere with the pink color, but the endpoint is still visible). When the color holds for about 30 seconds without fading, stop adding titrant.
  6. Read the syringe. Note how many mL you used.

Reading the Result

Here’s where the grade-school math comes in. Each milliliter of titrant you used equals 0.1% TA. So if you used 5.5 mL to reach the color change endpoint, your wine’s titratable acidity is 0.55%.

That’s it. Multiply the mL used by 0.1 and you have your TA percentage.

Most finished dry wines fall in the range of 0.55% to 0.75% TA. Wines headed below 0.55% often taste dull and may need acid added. Wines above 0.80% can taste sharp or sour and may benefit from techniques that reduce acid, like cold stabilization or blending.

Write your results down every time you test. Tracking TA at different stages — before fermentation, after fermentation, and before bottling — tells you a story about how your wine is developing.

When to Test

Test early and test often. Here are the three most important checkpoints:

  • Before fermentation (the must stage): This is your best opportunity to adjust acidity before yeast activity changes the chemistry.
  • After fermentation is complete: Fermentation can shift acidity, so it’s worth retesting before you make any final adjustments.
  • Before bottling: A final check ensures your wine is balanced and ready.

Skipping the pre-fermentation test is like seasoning a dish only after it’s fully cooked — you can still fix it, but it’s harder.

Why This Works

Here’s the mental model: imagine acid as money hidden in a jar, and sodium hydroxide as a magnet that pulls dollar bills out one at a time. Phenolphthalein is the alarm that goes off when the jar is empty. You count how many times you reached into the jar, and that count tells you exactly how much money — or acid — was in there.

Sodium hydroxide is a base, which means it neutralizes acid. Every time you add a small amount to your wine sample, it combines with some of the acid and cancels it out. The phenolphthalein stays colorless as long as there’s acid in the sample to react with. The moment the acid is fully neutralized, even a single extra drop of base makes the solution turn pink. That color change is your signal that you’ve reached the equivalence point — the exact moment when all the acid has been accounted for.

The amount of base it took to get there is a direct, proportional measure of how much acid was in your wine. That’s titration in a nutshell, and once you’ve done it a couple of times, it takes about five minutes and tells you something genuinely useful about what’s in your glass.