I’m not a father, but I am a teacher. Usually, I teach drama, but every Saturday I teach a class that combines science with debate.

So naturally, when you think of a scientific debate, the first place your mind goes to is sauerkraut, right? Hang in there.

In China, science class doesn’t typically involve experiments or any mention of hypotheses. Instead, students are taught the theoretical facts as scientists currently understand them, from a textbook.

Students read and copy the book, then are tested on how much they remember. Yay education.

The reason my class exists is that some parents feel that their children should be more involved in the scientific process.
So every week we learn a scientific theory, then build a hypothesis and test our belief with an experiment.

This week, we’re testing probiotic bacteria and the process of fermentation in a fun and delicious way that anyone can replicate.
So if you’ve never made sauerkraut before and would like to give it a try, this may be the excuse you need to finally try it out.

Let’s Get Fermenting!

Fermenting is really fun, and the result is highly nutritious. The probiotic bacteria that grow within the sauerkraut goes a long way in improving your gut microbiome.

So as we go into winter, the more fermented foods you can work into your diet, the more microscopic warriors you’re adding to your inner battlefield; ready to wage war on the bugs and viruses coming your way.

Here’s what you’ll need, how to get it done, and the science behind why it works.

You’ll Need

• a cutting board
• a sharp knife
• A glass far, preferably a fermentation jar with a burp lid
• A big mixing bowl, pot, or bucket
• 2 cabbages
• A packet of salt
• A few cloves of garlic

First, make the kids wait a few minutes while the grown-up cuts the washed cabbages into ribbons.

Make sure that while you’re washing the cabbages, that you aren’t being too vigorous. You want the dirt cleaned off, but you don’t want to lose the valuable yeast that grows and multiplies during the fermentation process.

Once the cabbage has been cut, place it into the bucket with enough salt. To find out how much salt you’ll need, check the cabbage packaging to find out how many pounds of cabbage you have. You’ll need 2 teaspoons of salt for every pound of cabbage.

Add the salt, then allow the kids to take turns getting their (thoroughly washed) hands in there.
Make sure you show the kids how to mix the cabbage properly. They’ll need to pick up handfuls of cabbage and squeeze as tightly as they can, trying to squeeze as much water out as they can.

The whole process should take half an hour to squeeze and mix the cabbage long enough that you’ve extracted enough water. If you’d like, divide the time evenly amongst the kids so that each one gets an equal turn.

After the last kid has finished mixing and the cabbage looks like a watery, limp mess; it’s time to throw in your skinned and crushed cloves of garlic.

Once you’ve added the garlic, you can then begin adding handfuls of cabbage and garlic into your fermentation jars.

After every few handfuls, I like to sprinkle a little more salt into the jar to give the bacteria some extra food to nibble on during their time in your cupboard.
Don’t go overboard though, you never want to have too much salt in the jar.

Then, once all of your cabbage has been added to the jar, fill it up with enough cabbage-water (the water your kids squeezed out of the cabbage) to completely submerge the cabbage and garlic.

It’s important to ensure that the cabbage remains submerged for the entire time that it’s fermenting, and there’s two good ways for making that happen.

You can buy glass fermentation weights that sit on top of the cabbage and weigh it down. Alternatively, you can fill a sandwich bag with water and fit it between the cabbage and the top of the jar.

The bag will keep the cabbage down, and the water will flesh-out the bag and keep it flexible so that it blocks all nooks and crannies in the jar. It’s important that no oxygen is allowed access to the cabbage.

Once you’re all done, wipe the jar off and store it somewhere cool and dark. You and your kids will need to resist for at least two weeks to ensure the fermentation process is complete.
If you’re someone that enjoys sauerkraut with a stronger bite to it, you can leave the jar in your cupboard for a month.

The Science at Work

The environment you’ve just created inside your jar is one that allows the lactic acid-producing bacteria that naturally live inside cabbage to thrive.

These bacteria cause the pH level inside the jar to reduce, making the environment acidic and unsuitable for the growth of bad bacteria.

While the environment is bad for bad bacteria, it’s perfect for all the lactic-acid-loving good bacteria that live inside cabbage. They will multiply and grow strong over the next two weeks they spend inside the jar.

Locking out the oxygen is important because these types of good bacteria can’t reproduce well when exposed to large amounts of oxygen.

These good bacteria gobble up all of the carbs inside the jar while growing and reproducing. After gobbling up carbs, they burp out carbon dioxide until all the oxygen still inside the jar is replaced with carbon dioxide. This is why it’s important not to use a regular jar.

Pressure inside the jar is going to build as more oxygen is replaced with carbon dioxide, so a weak jar may shatter. A fermentation jar is much stronger, and should have a lid on top that will burp carbon dioxide out when pressure builds too high.

You’ll know the ferment is finished when bubbles stop appearing inside the jar, although you don’t have to wait until then to eat it.

A Word of Caution to this Tale

Don’t eat any sauerkraut that doesn’t seem right. While the process is fairly foolproof, it’s not impossible for something to go wrong.

Luckily, the presence of bad bacteria is very easy to spot. If your sauerkraut smells disgusting, throw it out. The texture should be slippery, yet crunchy and sour. If the texture is slimy, it’s gone bad.

Lastly, if there’s any mold, don’t eat around it. Throw out the whole jar.

It’s a pain in the ass to throw out the entire ferment after all that waiting, but you never want to take a chance with bacteria.
Instead, allow it to be an opportunity to try the project again with your kids, and let it be a lesson on the importance of patience and resilience.

However, don’t stress about blue or green garlic. If your garlic changes colour during the process, that’s not a sign of mold. The change is a naturally occurring chemical reaction that takes place in the highly acidic enviornment, so don’t stress!

You’re All Set!

Fermentation is an exciting way to spend an afternoon with the kids. They’ll have a blast, and you’ll have a jar of delicious and healthy sauerkraut as a reward.

Plus, getting them to eat their greens is a lot easier if they’ve made it themselves and had to wait for two or four weeks to give it a try!

Once you’ve tried sauerkraut, why not move on to something more challenging?
Maybe pickles next, and eventually cheese! There’s a whole wide world of ferments out there that can fill many more fun afternoons.