Kimchi is the strong, spicy pickled cabbage.

It is a major standby of Korean cuisine.

Not only is it in Korean restaurants and homes everywhere, it's also popped up in trendy restaurants and food trucks throughout the world.

So what makes plain old pickled cabbage so successful?

Chemistry might have something to do with it.

There are plenty of kinds of kimchi but at its most basic it involves cabbage, onions, maybe some other veggies, garlic, fish sauce, and some other spices.

More than enough ingredients to give rise to some serious flavor chemistry.

But that's not all because kimchi, like all our favorite funky foods, is fermented.

Fermentation involves chemical and biological processes usually with the help of microbes creating desired changes in foods' nutritional content and shelf-life.

It also creates awesome flavors working together with all those tasty spices to make something even more unique.

It's actually pretty easy to make kimchi at home.

The first step is to salt the cabbage, and while salt is essential for flavor, this is also a chemical trick to soften the cabbage in a process called osmosis.

Osmosis happens when solutes on one side of a leaky barrier are more concentrated than on the other side.

In this case the solute is salt and the barrier is the cell membrane.

Water will diffuse across the cell membrane to dissolve the salt until the concentrations are more equal on both sides.

This will cause the cells to shrivel up a bit and the cabbage as a whole will become softer.

Now that the cabbage has been salted and softened it's time to ferment it.

How long to ferment your kimchi depends entirely on the temperature.

Kimchi fermented at room temperature might be ready in a few days, but it seems to lack flavor.

Some people make it in the fridge at about 4 degrees Celsius, which might be on the chilly side.

It takes a lot longer but it might develop more flavors over time.

During fermentation bacteria that are naturally present in the veggies begin to grow.

These helpful bacteria munch on food sources like starches and sugars in the kimchi mixture and leave behind acids.

Notably lactic acid.

Lactic acid fermentation is a very common method of food preservation.

The presence of acid and salt generally guarantees that other bacteria, ones that might spoil the food, have a harder time growing.

As acid is produced the pH of the kimchi decreases from a near neutral 6 to a more acidic 4.2 or so which means it's ready to eat.

Fermentation creates tasty molecules that contribute to kimchi's signature punch.

There's a study in the Journal of Agriculture and Food Chemistry which identified at least 77 molecules that contribute to the aroma of kimchi -- things from sourness and pungency to buttery cheesy flavors to floral and vegetal flavors.

There are all kinds of things going on in this dish right now.

So let's try it.

Mmm.

Ah.

There's the spiciness.

It's a slow burn.

The fruity flavors come from things like geranylacetone and beta ionone.

And it's good.

It's actually a nice strong sort of vegetable, fruity, floral flavor that comes from the cabbage.

Let's have another a little bit here because it's pretty tasty.

There's actually a buttery note in there and that develops as the fermentation goes along.

That's contributed by a molecule called 2,3-butanedione.

It's kind of a buttery and kind of cheesy.

The actual like sort of sourness was also a product of the fermentation.

That's the different acids, acetic acid is present in there, propionic and butyric acids are also in there so that contributes to the overall sourness.

Of course the garlic and the onions add a lot of flavor.

A lot of that is in the form of sulfur-containing molecules which have a very strong pungent flavor that you associate with onions and garlic, as sulfur containing compounds frequently do.

So now we know what gives kimchi its kick.

Unlike some of our fermented food episodes I'm not exactly going in blind here.

I'm no kimchi expert but I definitely had it before and I'm a huge sucker for sour pungent foods.

So this one gets the thumbs up from me.

Thanks for watching.

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