Radishes are one of the quickest vegetables to ferment. Sliced red radishes in a salt brine turn tangy in about 3–5 days, and the brine goes a deep pink as their colour leaches out; daikon and whole radishes take a week or so. Fermenting also tames their peppery bite.
What Fermenting Does to a Radish
In a 2026 analysis of lacto-fermented red radish, organic acids rose about tenfold and phenolic compounds eightfold, while glucosinolates – the compounds behind radishes’ pungency – fell to 16% of their starting level. The antioxidant mix shifted too, away from the red anthocyanins and towards flavonols and phenolic acids (Mróz et al., 2026). That’s the chemistry behind the milder taste and the colour moving into the brine.
The smell. Fermenting radish smells strongly sulfurous, sometimes like cabbage or eggs. That’s normal: volatile sulfur compounds are among the key aromas of fermented radish – in a study of Sichuan radish pao cai they were made by yeasts early on and lactic acid bacteria later (Zhao et al., 2026). Use an airlock lid, or keep the jar somewhere it won’t bother you. A rotten or putrid smell with sliminess is different – discard that.
Yellow daikon. Daikon pickles can turn yellow as they age. In Japanese takuan-zuke the yellowing comes from daikon’s own isothiocyanate, and it happens faster once the pH drops below 5 (Kobayashi et al., 2020). It’s harmless.
Which Radishes, and How to Cut Them
- Red globe radishes: slice 5 mm thick (3–5 days) or halve (5–7 days); they give the pinkest brine.
- Daikon: peel and cut into sticks or half-moons (5–10 days). For cubed radish kimchi, see kkakdugi in our kimchi variations.
- Watermelon and French breakfast radishes: slice or halve; milder.
Use firm, fresh radishes: soft, spongy ones ferment soft. Radish greens can go in too, but they soften faster. For other vegetables and their salt and timing, see our guide to the best vegetables to ferment.
Storage
Ferment until the radishes taste clearly sour – a properly soured brine is well below pH 4.6, the line US regulations use for acidified foods (21 CFR 114) – then refrigerate. They keep for weeks to a couple of months in the fridge, slowly getting sourer and softer. For films, softness or off smells, see the NCHFP’s problems with fermented pickles and our troubleshooting guide.
