Knowledge Base

Kimchi

Vegetable ferment · Traditional · peer-reviewed

Korea's national ferment — brined napa cabbage and a spiced paste, cultured cold and slow by Leuconostoc and Lactobacillus into a fizzy, sour, umami staple.

Moderate to make
3–14 days ferment
live-cultures, lactic-acid, vitamins supplied

Ingredients

  • Napa cabbage1 head
  • Coarse non-iodised salt (for brining)60 g
  • Korean chilli flakes (gochugaru)40 g
  • Garlic, ginger, spring onion, fish sauce (or soy for vegan)to taste

What it is

Kimchi is a family of Korean fermented vegetables, most often napa cabbage salted, coated in a spiced paste of chilli, garlic, ginger and fish sauce, then left to ferment by the lactic-acid bacteria native to the vegetables. It ferments cold and slow, which is what gives good kimchi its clean, effervescent sourness.

The science

Kimchi fermentation is driven overwhelmingly by lactic-acid bacteria of the genera Leuconostoc, Lactobacillus/Latilactobacillus and Weissella. Leuconostoc mesenteroides typically leads, producing CO₂ (the characteristic fizz) and mannitol, before more acid-tolerant lactobacilli take over and deepen the sourness (Jung, Lee & Jeon, 2014).

Temperature is the main control lever. Cold fermentation (around 4 °C) favours Leuconostoc and yields a milder, more complex, longer-lasting product, whereas warm fermentation acidifies fast and can turn sharp. Salt (~2–3% after brining) and the anaerobic paste coating select for LAB over spoilage organisms (Patra et al., 2016).

Safety

As with all lacto-fermented vegetables, safety rests on acidification under brine. Keep the cabbage submerged in its own liquid and let the pH fall below 4.6. Skim any surface film; discard for fuzzy mould or putrid odour.

Signs it worked / troubleshooting

  • ✅ Good: tangy, fizzy, savoury; bubbles when pressed.
  • ⚠️ Too sharp/sour = fermented too warm or too long → move to the fridge sooner next time.
  • 🚫 Mould or off smell = contamination → discard.

How to store

Kimchi is meant to keep fermenting slowly in the fridge, maturing over weeks to months. Press it back under the brine after each use.

References

  • Jung JY, Lee SH, Jeon CO (2014). Kimchi microflora: history, current status, and perspectives for industrial kimchi production. Applied Microbiology and Biotechnology 98(6):2385–2393. doi:10.1007/s00253-014-5513-1
  • Patra JK, Das G, Paramithiotis S, Shin HS (2016). Kimchi and Other Widely Consumed Traditional Fermented Foods of Korea: A Review. Frontiers in Microbiology 7:1493. doi:10.3389/fmicb.2016.01493
  • Park KY, Jeong JK, Lee YE, Daily JW (2014). Health benefits of kimchi (Korean fermented vegetables) as a probiotic food. Journal of Medicinal Food 17(1):6–20. doi:10.1089/jmf.2013.3083

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