A Hot Sauce That Kept Fermenting in the Bottle

5 September 2026 · 3 min read

The chilies came from the two plants on the windowsill plus a bag from the market: 640 g of mixed red fruit, mostly medium heat, a few hot ones for interest. I removed the stems, left the seeds, and ran them through the food processor with 4 cloves of garlic and half a small onion, then weighed the mash at 710 g and added 21 g of salt, which is just under 3 percent. Into a 1-liter jar, a small glass weight to hold the mash under its own liquid, and an airlock lid.

The first week was dramatic. By day two the mash had risen 3 cm and the airlock bubbled every few seconds; the kitchen was 23 °C and the smell was pure fresh chili with a sour edge coming in by day four. Activity slowed through week two and had nearly stopped by day 21, when I tasted it: sharply sour, fruity, still hot, with a slight funk from the garlic that I like. The pH strip read about 3.4, which is comfortably below the 4.0 I treat as my safe line.

I blended it smooth with 80 ml of the brine that had collected and about 40 ml of white vinegar, bottled it into two small sauce bottles with screw caps, and put them in the fridge. That was the mistake, or rather the half-mistake. Every morning for a week the caps hissed when I opened them. The sauce was still fermenting, slowly, in the cold. The second bottle developed enough pressure that it spat sauce across the fridge door when I cracked it.

What I should have done, and will do next time, is one of three things:

Heat the blended sauce to about 85 °C for a few minutes to stop fermentation, at the cost of some of the fresh flavor.
Add considerably more vinegar, bringing the pH down toward 3.0, which the yeasts and bacteria tolerate poorly.
Use bottles with flip-top or loose caps for the first two weeks and vent them daily, then tighten once they go quiet.

I went with the third option for the remaining bottle, and after ten days it stopped hissing. The sauce is excellent on eggs. The fridge door has a faint orange stain that I have decided to think of as seasoning.