4 min read
What happens inside the crock?
Fermentation, day by day
Once the kimchi goes into the fermenting crock, most of the work is no longer done by us but by microbes. Here's what goes on under the lid: why it fizzes, why it sours and why it's a little different every day.
It all starts with salt
Salt draws water out of the cabbage leaves, and that becomes the brine the fermentation happens in. Salt holds back unwanted microbes and makes room for the ones we need: lactic acid bacteria.
They live naturally on the vegetables and spices. We don't need to add them; we just need to give them the right conditions.
The first days: bubbles
Early on, the main workers are lactic acid bacteria called Leuconostoc. They turn the vegetables' sugars into lactic acid, a little acetic acid and carbon dioxide.
The carbon dioxide is the fizz. It's why the brine sometimes rises and why the jar hisses when you open it. That's a good sign: the fermentation is alive.
Halfway: it sours
As more and more acid forms, the brine becomes more acidic. In an acidic, airless environment most unwanted microbes can't grow. That's how fermentation has preserved food for centuries, without preservatives.
Meanwhile the cabbage turns more translucent and the chili and ginger work their way into the leaves.
Towards the end: the flavours come together
Later, more acid-tolerant Lactobacillus and Weissella species take over. The souring slows and the flavours round out.
Exactly when this happens depends on temperature, salt and the vegetables. That's why we taste it every day, and why we say the flavour decides, not the calendar. You can see where the current batch is up to in the live feed.
It doesn't stop in the fridge
When the flavour is right, the kimchi goes into the fridge. Cold slows fermentation right down but doesn't stop it: kimchi keeps maturing in the fridge and gets a little sourer week by week.
That's why Korean cooking uses fresh and mature kimchi differently. Fresh kimchi is eaten as a side; older kimchi goes into cooking, such as stews or fried rice.
Storage tips
- Always keep it in the fridge, tightly closed.
- Use a clean, dry utensil to take some out.
- Press what's left back under the brine so it isn't exposed to air.
- If the jar hisses or fizzes a little, that's normal, so open it gently.
- It smells strong, so the rest of your fridge will thank you for a container that seals well.
- If you see mould or it smells rotten, don't eat it.