This method runs on a vacuum sealer. Got one? You’re halfway there. Don’t have one? Buy one — it’s the whole trick.
Salt plus no oxygen lets the good bacteria (lactobacillus) turn the sugars in your peppers into lactic acid. That sours the mash and preserves it. A vacuum bag is airless from the moment you seal it, so unlike a jar there is no surface for mold to grow on.
1. Prep
- Wash everything. Pull the stems off the peppers.
- Rough chop or slice — more surface area means a faster ferment.
- Garlic, onion, carrot and fruit all ferment happily alongside peppers.
- Wear gloves with anything hotter than a jalapeño, and keep your hands away from your eyes.
2. Salt — this is the safety net
- Weigh your peppers and produce, then add 2–3.5% of that total weight in salt. This app defaults to 2.5%.
- Use non-iodized salt — kosher, sea or pickling. Iodine slows the ferment down.
- Don’t drop below 2%. Salt is what holds the bad microbes back while the good ones get established.
- Toss until evenly coated and it starts to weep liquid.
3. Seal it
- Cut the bag long. At least 12 inches, and 18–24 inches is better. The extra length gives the gas somewhere to go, and lets you snip the top and re-seal a few times without running out of bag.
- Use a gentle or moist setting, or chill the mash first. On full power the pump will pull brine straight into the machine.
- Leave plenty of headroom above the mash — it needs room to expand.
- Double-seal the top edge if your sealer lets you.
4. Let it ferment
- Room temperature, out of direct sun — 65–75°F / 18–24°C. Warmer ferments faster.
- Stand the bag in a tray or tub. Bags do sometimes leak, and brine stains.
- The bag will usually puff up with CO2 within a few days — a good sign, though not every batch does it (see below).
- If it gets balloon-tight, snip a corner, press the gas out and re-seal — or use valve bags and skip the burping.
5. Signs it’s going well
- The liquid turns cloudy and the bright colors dull toward olive.
- It smells clean and sour, like a good pickle.
- Gentle fizzing when you open it.
- 1–4 weeks is the usual range. Two weeks is a solid default — taste it and decide.
Two things that look wrong but aren’t:
A cloudy white film — that’s Kahm yeast. Harmless. It can add a slightly funky flavor, so skim it off or blend it in as you prefer, but it’s not a reason to bin the batch. Kahm is flat, white or cream, and filmy; mold is fuzzy, raised and colored (blue, green, black, pink) — that one you bin.
A bag that never really puffs. Lacto behaves a little differently every time, and not every culture throws off much CO2. A quiet bag can still be fermenting perfectly well — go by smell and taste, not by how tight the bag gets.
6. When to throw it out
Bin the batch if you find fuzzy or colored mold, a putrid or rotten smell (sour is good, rotten is not), or an unusual slimy texture. When in doubt, throw it out — it’s a bag of peppers, not worth the risk.
7. Bottling
- Blend it, then strain if you want a thinner sauce.
- Add vinegar to taste — and for keeping quality.
- Anything stored outside the fridge should be at pH 3.8 or lower. Check it with a meter or test strips, not by guessing.
- Not bottling shelf-stable? Just keep it in the fridge and use it within a few months.
Why those two numbers matter: an airless, low-acid environment is the one situation botulism bacteria like. Your salt level going in and your final acidity coming out are what rule that out — so treat 2%+ salt and pH 3.8 as the limits, not suggestions.
These are general guidelines to get you started. If you’re preserving for the long haul, follow a properly tested recipe.