Fermentation gives chilli sauce depth and a rounded acidity – it is an old method, the same principle as sauerkraut. To keep the sauce safe, follow a few rules: enough salt, everything under the brine, and a pH of 4.6 or below.
.jpg){kind=link}
No extension service or food-safety authority has yet published a tested recipe specifically for fermented hot sauce. Below we summarise the general vegetable-fermentation rules from US university extension services (K-State, University of Illinois, UC Davis, NCHFP) and findings from scientific studies on fermenting peppers.
What you need
- chillies (any variety or mix, e.g. habanero or Tabasco)
- non-iodised salt (e.g. pickling salt)
- water
- a jar, a weight (a small jar or a bag of water), ideally a lid with an airlock
- a pH meter with pH 4.0 and 7.0 calibration buffers
How much salt
For peppers, Kansas State University recommends a stronger brine than for other vegetables – roughly 5%. The University of Illinois gives 45 g of salt per quart (0.95 l) of water for a 5% brine. Don’t cut the salt; extension services warn that less salt endangers the ferment. Beware the other extreme too: in a study of habanero mash with 5–25% salt, pH fell only to 4.47–4.78 over 50 days – above the safe limit. That is why you must measure pH.
Method
- Wash the chillies, remove the stems and chop or roughly blend them. Wear gloves (see safety).
- Put them in a clean jar and cover with 5% brine so that they are fully submerged (Illinois recommends 1–2 in / 2.5–5 cm). Weigh them down.
- Close with an airlock lid, or “burp” the jar daily by loosening the lid.
- Ferment at 15–22 °C – according to K-State a slower, cooler ferment gives better results. At 20–22 °C it usually takes 3–4 weeks according to Illinois; in the cold, 6 weeks or more.
- Measure the pH. The safe limit is 4.6 or below – below it the botulism bacterium cannot grow. In a study of C. frutescens, pH fell from 5.3 to 3.1–3.9.
- Blend the peppers with some of the brine to the consistency you like and store the sauce in the fridge; at room temperature it would keep fermenting “beyond palatability and safety” (K-State).
How to measure pH properly
According to the Nevada Department of Agriculture, pH strips are not accurate enough, and the colour of chilli distorts them anyway. Use a pH meter calibrated with pH 4.0 and 7.0 buffers on the day of measuring, measure at room temperature, and blend the solids into a slurry, adding a little distilled water if needed.
Kahm yeast or mould?
- Normal: a white, grey or even pinkish film on the surface is usually kahm yeast – skim it off from time to time (UC Davis). According to the University of Illinois, kahm is not fuzzy and does not form round patches.
- Discard everything: fuzzy mould (green, blue, brown, black), slime, soft pieces or a putrid smell (UC Davis, NCHFP).
Garlic yes, oil no
Garlic in a ferment is fine as long as the pH drops to 4.6 or below. The real botulism risk is garlic or fresh chilli in oil – see chilli oil.
The same principle – fermenting chillies with salt – is also where Sakay sauces begin.
Safety: wear gloves when cutting hot chillies and do not touch your face. If you do not wear gloves, wash your hands thoroughly with soap before touching your eyes.
Sources
- Krug M. (2020): Fermenting vegetables, Kansas State University MF3491
- University of Illinois Extension: Fermenting; Fermenting FAQ
- NCHFP: General information on fermenting
- DiCaprio E. et al. (2022), UC Davis: Troubleshooting fermented fruits and vegetables
- Nevada Department of Agriculture: Measuring pH
- Vegas C., Zavaleta A. I., Zarzoso B. (2018). Agronomía Colombiana 36(1): 89–97. doi:10.15446/agron.colomb.v36n1.69164
- Aryee et al. (2022): Characterizing fermented habanero pepper. Food Chemistry Advances. doi:10.1016/j.focha.2022.100137