How We Test Acidity (and Why 5% Matters)

Every batch of vinegar I make has to pass a pop quiz before it ever gets a label. 📝 It's not a taste test (although I do plenty of those 😋). It's a chemistry test, and it involves a syringe, a few drops of indicator, and me hunched over a tiny glass of vinegar waiting for it to blush. 🩷

Here's what's going on, and why that one little number on our labels matters so much. 👇

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🧪 WHAT "ACIDITY" ACTUALLY MEANS

When you see "5% acidity" on a vinegar bottle, that's telling you how much acid is in there, mostly acetic acid, the compound that gives vinegar its signature tang. ⚡

Acetic acid is what the acetobacter in my generator produce when they convert wine into vinegar. 🍷➡️🫙 More conversion, more acid.

💡 Label lingo: You'll sometimes see "50 grain" on older or commercial labels. 5 percent acidity and 50 grain mean the same thing, just different units.

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🩷 HOW WE TEST IT: TITRATION (A.K.A. WAITING FOR THE PINK)

Titration sounds intimidating, but it's the same method students learn in high school chemistry. 🎓 Here's the short version:

1️⃣ I measure out exactly 2 mL of vinegar. 2️⃣ I add a couple drops of phenolphthalein, an indicator that stays clear in acid. 3️⃣ I slowly add a sodium hydroxide solution (a base) drop by drop, swirling the whole time. 🌀 4️⃣ The base neutralizes the acid. The moment all the acid is used up, just one more drop turns the solution from clear to a very pale pink. 🎉 That's the finish line!

🧮 The math is delightfully simple: because of the specific strength of solution I use, I divide the milliliters used by 2, and that's the acidity percentage. Used 10 mL? That batch is 5% acidity. ✅

🌈 A fun wrinkle: some of our vinegars are gorgeous shades of red, orange, and purple, which makes spotting "pale pink" a little like finding a pink sock in a pile of red laundry. 🧦😅 Diluting the sample helps. Even red wine vinegars, once diluted for titration, are usually pale enough to see the color change.

🤓 Nerdy honesty note: this method measures total acidity and credits it all to acetic acid. Live, co-fermented vinegars contain small amounts of other flavorful organic acids too, which is part of why ours taste more complex than the plain stuff. ✨

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🎯 WHY 5% IS THE MAGIC NUMBER

The acidity level isn't just about flavor. It's about food safety. 🛡️

📚 The tested recipes from the USDA Complete Guide to Home Canning and the National Center for Home Food Preservation are built around vinegar at 5% acidity.

😮 Here's the surprising part: the FDA only requires vinegar to contain a minimum of 4% acetic acid, and 4% white vinegar has been showing up on store shelves in recent years.

⚠️ That 1% difference sounds tiny, but vinegar below 5% isn't considered adequate to control microbial growth in home canning.

✅ That's why we test every batch. Our vinegars and DIY pickle brines are produced to approximately 5% acidity.

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🍳 WHAT THAT MEANS IN YOUR KITCHEN

🏷️ Always check the label. Buying grocery-store vinegar for pickling? Look for 5% or 50 grain. Don't assume!

📖 Use tested recipes for canning. For shelf-stable canning, white distilled and cider vinegars at 5% are the recommended standard, and safe canning recipes haven't been developed for wine vinegars. That's why we recommend our live vinegars and DIY pickle brines for refrigerator pickling only. ❄️

🥕 Want our flavor in your pickles? Mix 1/4 cup of our live vinegar with 1 cup of regular white vinegar for a flavor boost, and keep those jars in the fridge.

🦷 Don't drink it straight. Five percent acid is strong stuff! Dilute your drinking vinegar in sparkling water, tea, or lemonade to be kind to your tooth enamel. 🥤

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💚 THE BOTTOM LINE

Great vinegar is equal parts art and science. 🎨🔬

The art is in the fruit, the herbs, the patience, and the months of slow fermentation. 🍒🌿⏳ The science is a 2 mL sample, a few drops of indicator, and a very satisfying pink. 🩷

We do both, every batch, so every bottle that leaves our kitchen is as safe as it is delicious. 😋

✨ Turning bland into grand, one pink drop at a time. ✨

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📚 REFERENCES

🔗 National Center for Home Food Preservation. General Information on Pickling. https://nchfp.uga.edu/how/pickle/general-information-pickling/general-information-on-pickling

🔗 University of Illinois Extension. 5% Acidity Vinegar Is Key to Safe Canning. https://extension.illinois.edu/news-releases/5-acidity-vinegar-key-safe-canning

🔗 UC Master Food Preservers of Central Sierra. About That Vinegar: Read the Label! https://ucanr.edu/site/uc-master-food-preservers-central-sierra/article/central-sierra-about-vinegar-read-label-edc

🔗 University of Wisconsin Extension. Vinegar with 5% Acidity: It Matters. https://iowa.extension.wisc.edu/files/2023/07/Vinegar_July2023-002.pdf

🔗 Chemistry LibreTexts. Titration of Vinegar Lab Procedure. https://chem.libretexts.org/Ancillary_Materials/Laboratory_Experiments/Wet_Lab_Experiments/Chemistry_410:_Chemistry_for_Health_Sciences_Laboratory_Manual/09:_Titration_of_Vinegar/9.01:_New_Page

🔗 Validation of Rapid Enzymatic Quantification of Acetic Acid in Vinegar (PMC). https://pmc.ncbi.nlm.nih.gov/articles/PMC7353505/

🔗 Titrations.info. Determination of Acetic Acid in Vinegar by Titration. https://www.titrations.info/acid-base-titration-acetic-acid-in-vinegar

📖 Malle, Bettina & Schmickl, Helge. The Artisanal Vinegar Maker's Handbook. Spikehorn Press, 2015.

*authored with assistance from ChatGPT