Heads up! This is a very long read and is therefore split up into 4 different parts.
- Kimchi Fermentation Part 1: A Short History
- Kimchi Fermentation Part 2: Good Bacteria vs. Bad Bacteria
- Basic Kimchi Techniques Part 1: The Pre-Brine
- Basic Kimchi Techniques Part 2: Foolproof Fermentation
(Don’t worry, I will never sell your email address, send you spammy emails, or anything of that ill nature. Although I do know a Nigerian prince that might need a little help…)
History of kimchi in Korea
A long long time ago, there were no refrigerators. Or freezers. Or any sort of food preservation methods that we commonly use now. If you wanted to keep your food fresh, you had to turn to other methods to do so.
One of these methods was fermentation. Most likely an accidental discovery, the fermentation process became a way of preserving vegetables for later. As early as 300 AD, Koreans were already experimenting with fermentation, brewing and pickling according to the Book of the Three Kingdoms. The early forms of kimchi most likely were very simple vegetables preserved with salt – the cabbage kimchi with red pepper we are familiar with was a more modern invention.
Throughout the Koryeo period (918-1392 AD) kimchi likely evolved to incorporate more vegetables, herbs, and the fermented seafood dishes called jeotgal.
In 1500, the red chili pepper made it’s way over from the New World to Korea through Portuguese trading with the Japanese. Dried chili pepper powder was soon found to be an excellent addition to the fermented vegetables, and eventually the napa cabbage kimchi we are familiar with today was born.
A short overview of fermentation
OK So, we get it. Kimchi is a dish made of fermented cabbage. Cool. But what exactly is that? And why does it kind of sound a bit disgusting when you put it like that? Fermenting sounds icky, and fermented cabbage sounds ickier.
Here’s the thing: people have been fermenting food for years. In fact, a lot of foods we enjoy in modern times are either fermented or were fermented at some point. Everyday foods like ketchup, beer, cheese, salsa, soy sauce, vinegar, wine, sour cream, yogurt and sourdough bread were all made traditionally by allowing food to grow a little bit of yeast or bacteria.
Wait! Don’t freak out just yet. I’ll get into why that’s not such a bad thing in a bit. The funny thing is, by growing a bit of yeast or bacteria, the food not only doesn’t spoil, it becomes much more nutritious and (in many cases) much more delicious!
These bacteria that are performing the fermentation are also completely harmless to people (as opposed to the ones that would give you food poisoning) and may even have been the key to good health and increased nutritional content. (We’ll get into the friendly bacteria and nutritional benefits in a later post)
But let’s go back to why? Why allow your food to literally start decomposing? Who the heck decided to leave out cabbage until it started rotting, then decided to EAT IT? First of all, there were no fridges back then, and there were also no preservatives like the ones we have today in the food processing industry. That meant that if you couldn’t quickly eat what you had, and there was no way of drying it safely, you would have to throw away what you couldn’t eat. In the case of cabbage, it was a very valuable source of vitamins, minerals, and all sorts of good stuff that people would want to have available as frequently as possible. You had to find a way to make the cabbage last, especially through the cold and bitter winter if you wanted to survive.
Most likely, it was discovered by accident – someone must have left some cabbage out, found that it wasn’t too bad after leaving it a few days and surprisingly that it didn’t kill them after eating (My guess it must have been the ancestor of foul bachelor frog)
However gross it was, an important discovery had been made: there were ways to preserve cabbage and other vegetables that would allow you to keep it for long periods of time. This would also allow you to stockpile veggies when you had an awesome harvest for the times when you did not have have so great of a harvest.
Through trial and error, people started experimenting with fermentation and preservation, finding different methods and techniques to preserve vegetables and food. Kimchi would be one example, using a salty brine to create the perfect environment for hosting the bacteria to ferment cabbage.
Next time, we’ll talk about the friendly little bugs that are doing the fermentation, and how exactly Koreans are able to encourage these good bacteria to grow in their kimchi.
Do you like fermented foods? And do you have a favorite? While I love kimchi, I also love Greek yogurt as well as all matter of soft cheeses. Let me know your favorite fermented foods in the comments below!
Good bacteria vs bad bacteria
Right, so in the last post we covered a short history of fermentation. Remember, the fermentation process generally does three very beneficial things
- Increases nutrition
- Changes or amps up the flavor
As we mentioned previously, this occurs as a result of good bacteria fermenting the food item. When it comes to fermented foods, the bacteria changes the original food item completely. A sweet and mild flavored cabbage leaf becomes a mouth puckeringly sour and spicy treat when it becomes kimchi. A bottle of cream becomes a thick and tangy yogurt. It’s quite frankly, a bit of transformative magic.
Let’s talk a bit more about these good bacteria in depth. Generally speaking, many of the bacteria used for fermentation come from the same clique of bacteria: Lactobacillus. These bacteria generally thrive in an acidic environment, and will oftentimes give the food a bit of a tangy or sour taste. The sour sharp taste of kefir or the slightly sweet-sour taste of sourdough is due to the bacteria breaking down the food. Our friends Lactobacillus are a group of bacteria that like to eat what we like to eat – flour, starches, milk, fruit, and vegetables.
Although there are other bacterial families that are involved with fermentation including Streptococcus, Leuconostoc, and Pediococcus, for the purposes of our discussion we will focus solely on the Lactobacillus gang and their role in fermentation.
The brave heroes of this story are the dark purple rod-shaped Lactobacillus. Photo Credit: Janice Carr Content Providers(s): CDC/Dr. Mike Miller
Who Are Lactobacillus?
Lactobacillus are very friendly little creatures. They are generally considered harmless or symbiotic microbes that are commonly found in the human urinary, digestive, and genital tracts (The bacteria probiotic proponents talk about are most likely Lactobacillus, which are important for maintaining a healthy gut and general well-being)
The particular guy we are interested in for kimchi is unsurprisingly named Lactobacillus kimchii. When making kimchi, our main goal is to ensure that we create the ideal home for this little friend to grow and thrive.
How To Lay Out the Welcome Mat for Lactobacillus kimchii
So, we are looking to have Lactobacillus bacteria grow in and around our kimchi. How exactly do we do that?
If you are like myself or any other human being, you may have left food for a bit too long in the refrigerator. Upon further inspection, you see that there are mold colonies starting to form fuzzy, black, or powdery forests and spots all over the once-edible food. This is NOT what we want – this is an uncontrolled bacterial free-for-all lovefest.
You may possibly have some beneficial bacteria somewhere in that mess, but the majority of it is stuff that could be unpleasant, toxic, possibly even fatal.
Our job with fermentation is to eliminate the bad bacteria and encourage the good bacteria
So the way we narrow down the types of bacteria that will eventually grow on the cabbage and make it into kimchi is by creating the perfect environment to encourage them to grow. We do this by controlling for two main factors: salinity and oxygen
Salinity, or how salty the environment in, is very important. It’s the same reason why you can’t keep freshwater fish in saltwater. You put freshwater fish in saltwater, they won’t survive – they’ll die (Please take my word on this and do not experiment with tropical fish. No fish were harmed in the research and creation of this post!)
Just like aforementioned tropical fish, only certain bacteria will survive in salty environments. By adjusting the level of salt in water, you can set up an environment that fosters the kind of bacteria you want (the friendly, non-toxic, acidic loving Lactobacillus kind). Other types of bacteria that might be undesirable (due to the fact it might spoil your kimchi and make you sick) generally cannot and will not survive in a salty environment.
How salty are we talking about? The 2-3% salinity range is the one we’re looking for. This appears to be the absolute ideal condition in which Lactobacilli are happy to eat, multiply, check Facebook, and do whatever else the Lactobacillus do.
Okay, so we’ve setup a reasonably salty environment and convinced a bunch of bad bacteria that sorry, they aren’t welcome in our kimchi. The next thing we can control for is oxygen. Or, more properly speaking, the lack of oxygen (more on this in a minute)
Now generally speaking when it comes to most things humans eat, we generally go for oxygen-rich foods. We don’t go for foods that have been kept in an oxygen-free environment because most of the time, an oxygen-free environment is a rotting, stinky mess. Think of muck from the bottom of a pond, sewers mess, or a turkey noodle casserole that has been stuck in the fridge for months. Yuck.
Yes, that is what usually happens, unless we have carefully setup the environment. We can actually work with bacteria in an oxygen-free environment so the bacteria will, instead of creating a stinky disgusting rotting mess, will create a delicious and tangy concoction.
How do you do that? Well, remember our friend lactobacillus? Lactobacillus is a very hardy bacteria (the fancy term being called a facultative anaerobe). Hey, stop, don’t go just yet – I promise I’ll explain why this is important in a second!
A bacteria that is a facultative anaerobe means that it can survive both with and without oxygen. Most critters do not have this capability. Exhibit A) Imagine yourself, an attractive and happy and vibrant human being. With oxygen? Great. Without oxygen? Pretty dead.
Unlike weak pathetic you however, this supernatural little bacteria does just fine without oxygen. It even PREFERS it because an environment without oxygen is generally less crowded with other bacteria, meaning less competition for space and food and other resources (more on this later).
(Note: If you’re a microbiologist, this would be an opportunity for you to start nerding out about aerobic and anaerobic environments and the prevalence of gram-positive bacteria. We’ll wait until you’ve got it all out of your system, then continue.)
Like I said, an oxygen-free environment is easier to compete in if you’re Lactobacillus, because there aren’t a lot of bacteria that do well in it. The whole “Big Fish in a Small Pond” thing. (Really everything we’re doing fermentation is trying to tip everything in favor of Lactobacilli conquering this little environment) If we setup the kimchi to where it is not exposed to oxygen, the Lactobacilli will be able to really multiple quickly and edge out 99% of the rest of the bacteria.
So, in addition to having eliminated a lot of bacteria from growing by creating a salty environment, on top of this you remove oxygen from the environment to FURTHER eliminate the bacteria that can survive. Survive of the fittest it is, and our friend Lactobacillus rises to the top!
BONUS: Red Chili Pepper
Interestingly enough, the red pepper commonly found now in kimchi actually also appears to have antibacterial properties as well. Although older methods of fermentation did not rely on red pepper (and instead relying on salt and lack of oxygen) the more modern versions of kimchi appear to have additional help with red pepper in narrowing the type of bacteria that can be cultivated. Chili peppers may inhibit many types of bacteria that have the potential to cause foodborn illnesses including E. coli, Salmonella, and Listeria (Antimicrobial Properties of Chili Peppers)
So, as if the salinity and oxygen-free environment weren’t enough, red chili peppers reduce the amount of bad bacteria EVEN FURTHER. How cool is that?
In the next post, we’ll talk about the basic techniques of how to setup your kimchi to foster Lactobacillus kimchii and set yourself up for success!
The law of attraction: setting yourself up for kimchi succes
As we went over previously, one of the important things about kimchi is the salt to water ratio. It’s probably the most important factor in making sure your kimchi is successful. The bacteria we want will thrive in the correct environment, but will die quickly if it is the incorrect one. Even more importantly, the bad bacteria will quickly multiple if the environment is off – but they will also be quickly killed off the environment is setup correctly
If you remember from the last post, the magic number is 2-3% salinity. At this salinity, most bacteria cannot survive with the exception of the good Lactobacillus bacteria we want.
The question is, how do we ensure this environment is created? And then, how do we make sure we maintain it while the Lactobacillus bacteria gets established in the kimchi?
The way to ensure that the bacteria gets a nice salty home is due to salt added at two points in the kimchi-making-process : the pre-brine and the post-brine. We’ll be covering the pre-brine in this post.
The pre-brine is done to start softening up the veggies and get a lot of salt in. By salting during the beginning, this ensures the ingredients get saturated uniformly with salt so they will ferment properly.
While this sounds quite possibly very complicated, it really isn’t. It usually just involves sprinkling a generous amount of salt over the vegetables and letting the vegetables sit for a couple hours.
By letting the salt and veggies sit for a while, this will allow for the salt to penetrate in as well as allow for water to exit out. This is technically the water that was being held in the cells of the plant material that is now pulled out by the salt.
How much salt to add?
As long as the veggies are well covered, it doesn’t matter too much. The exact amount isn’t super important in this case, as you actually rinse off a lot of this salt when preparing the kimchi.
How long do I let the vegetables sit?
I usually let mine sit for around 2-4 hours. This is usually enough to release quite a bit of the intracellular water and let the salt penetrate through the vegetables. You can leave it longer, but no longer than 6 hours – at that point, you start getting some really salty kimchi as well as creating an environment a bit saltier than our desired Lactobacillus prefer.
What type of salt do I add?
This is very important. Make sure the salt you’re adding is NON-IODIZED.
Iodized salt, in addition to making your kimchi taste gross, will also prevent bacteria from colonizing your cabbage (iodine, in addition to being a vital nutrient that was added to salt, also has antibacterial properties)
Generally speaking, the kimchi-safe types of salt I use either are kosher salt or a non-iodized sea salt.
How do I know when my cabbage or other vegetables are done pre-brining?
Your vegetables by the end of the pre-brine should go from being sweet, fresh and crisp to something a bit more limp and malleable. The veggies should still have a bit of crunch and snap to it – but will be a bit softened. Think of it as vegetable al dente.
Now, this is the second reason why we do a pre-brine: to make everything more packable. When the vegetables are raw and fresh, they’re all stiff and full of water. Great if you’re looking for a crisp and fresh salad with some crunch, but bad if you’re looking for kimchi. By pre-brining, the veggies become much floppier and are easy to pack together.
Have any questions regarding the pre-brine? Leave them below, and I will answer them! Stay tuned for the next post, we’re going to talk about the secret ingredients that we add to this salted vegetable material to make it into delicious kimchi.
Alright, so you’ve got salty cabbage. That’s great. Definitely not kimchi though. What do we do now?
Since we don’t have a magic kimchi machine (although I’d totally buy one if that were a thing) we’re going to use the lessons we learned about lactic acid fermentation in previous posts to turn our salty cabbage into yummy, tangy, probiotic kimchi.
So to review, we have three things that are necessary to ensure that we get friendly bacteria to colonize our salty cabbage.
- Lack of oxygen (anaerobic environment)
- Red chili peppers
Let’s focus on #2 first. There are a couple ways to cut off the salty cabbage from oxygen – some of which require fancy and complicated equipment and other techniques that are much simpler. Let’s take a look at some of them
A simple plastic bit of tubing, these guys are a way to ensure that you have a 100% anaerobic enviroment. These are frequently used by the homebrewing crowd. Some people swear by them for fermentation, but I haven’t found a need to use them, achieving decent fermentation for kimchi in other ways.
If you’re interested , these airlocks from Socal Home Brew seem to get good reviews for brewing and fermentation
Or if you are of the DIY nature, check out this straightforward tutorial from Northwest Edible Life to see how to assemble one on the cheap using a mason jar and parts from your local homebrew store.
These guys are the way to go if you’re looking to go fully authentic in your fermentation process. If you’re all about doing things 200%, looking to ferment items for a longer period of time (such as sauerkraut, which takes several weeks), or are just looking for fermentation expert bragging rights, then you can get one of these fermentation pots.
These puppies are like the Cadillacs of fermenting containers. Made of ceramic, they have weights that you can place on top of your salty cabbage, creating a fully anaerobic seal that will allow for carbon dioxide and other gasses during the fermentation process to escape, but will not allow for oxygen to penetrate in.
Granted, they are rather spendy, but if you’re looking to do a lot of fermenting, they might not be a bad investment.
Plate and a Rock
Let’s say you want to do things in a bit more of a rustic fashion. There is the good old plate and rock combo that allows you to create an oxygen free environment.
Very high tech, it involves a plate that rests on top of the cabbage, and a heavy (and clean) rock to weigh down the plate.
While I’ve used this system before, I always got a little skeeved out at the idea of placing a rock into the kimchi. You may not know what the rock is made out of, or what could leach out of it in terms of trace minerals or metals. Then, there’s always the fact that you never know where the rock has been and what it could introduce despite all the bleaching and scrubbing and soaking I could do.
You could always use something else to weigh the plate down. A bag of marbles, or a clean container full of water or rocks could be used just as easily. However, there’s a technique that is quite a bit easier, and since I tend to be rather lazy when it comes to certain things, this is my chosen method…
Kee-ju’s Lazy Kimchi Fermentation Method
Since kimchi usually only needs to be fermented for a few days, we have the luxury of not having to be quite as careful with the oxygen -free/anaerobic environment as we do with something like sauerkraut, which takes weeks to properly ferment.
My method of ensuring that we create an oxygen-free/anaerobic environment is quite simple: pack in firmly and submerge in liquid
Packing the cabbage firmly
Remember when we talked about how it’s a good thing that the cabbage goes limp after the pre-brining process so that it is easier to pack into a container? By packing in the cabbage as firmly as possible, it will ensure that we get a solid block of firmly packed vegetable matter. This accomplishes several things:
- Ensures that no air pockets remain – By leaving any pockets of air, you could inadvertently create an oxygenated area that could cause bad bacteria to grow in that spot. By making sure the cabbage is firmly squished down into the container, we eliminate that possibility.
- Keeps everything in place – Jammed into place, we want to make sure there aren’t any loose bits or pieces that will float up once we add the brine. You want it to be like a bale of hay – everything packed together so tightly that you would theoretically be able to pick it up as a solid block.
- Allows you to pack more vegetable matter into the container – More cabbage in the container = more tasty kimchi 🙂
So how do you pack the cabbage in firmly? You can use a clean spoon or a spatula, or even a wooden block to press the material down, but I prefer to use what my momma gave me: my own two hands.
You see, just like in other aspects of cooking and baking, there really isn’t anything like your own hands. The amount of fine pressure and force you can apply as well as the tactile feedback you get from your hands is for the most part unmatched by any utensil or machine (although this kimchi packing robot is pretty cool to see in action!)
The only thing I suggest is to always use protection.
(Yes, when making kimchi. No, no comment on that other thing. That’s a personal choice.
(I know, a million dirty jokes dealing with “packing firmly” just cried out in terror and were suddenly silenced. Deal with it. )
A pair of plastic or nitrile gloves, or a sturdy pair of utility gloves will keep your hands from getting covered in garlic, red pepper, and salt, and makes for a much more pleasant experience (as well as much more sanitary).
There really isn’t much to it aside from gloving up. Just squish and pack the salted cabbage down into your container. If you’re using a clear glass container, look to make sure there are no air pockets.
Stop adding cabbage so you have an inch or two of space left at the top. This will be important in performing the next step…
After you’re done packing the salted cabbage down firmly into the container, you’re almost done with this part! The last thing is to cover with a brine solution.
As you may remember from our lessons on salt and Lactobacillus, our desired salinity is 2-3%. While we can do all sorts of conversions, weighing salt and water and break out the salinometer, there’s a very easy-to-remember formula that will get you to that desired salt:water ratio within a few margins of error.
1 tablespoon of salt : 1 cup of water
(Yes, it’s not the most accurate, and yes I know technically it can vary due to grains of salt size. But it works, and will give you the desired outcome of safe, delicious kimchi.)
I usually mix up 2 cups of brine after I’ve packed in the salted cabbage mixture. This usually will be enough to cover all of the cabbage mixture and submerge it totally in the brine.
If at this point, you notice any pieces coming loose or floating to the surface, you can either remove them or try packing them down more firmly to get them to stay under the liquid. It’s important to ensure everything stays under the liquid – otherwise, you give opportunity for bad bacteria to start growing, and it could contaminate your whole batch of kimchi.
Okay, so we’re done packing and submersing the cabbage. But it’s not quite kimchi yet. I mean, you could eat it now, but it’s just salty and spicy cabbage (which isn’t horrible in it’s own right, but won’t quite be the magical experience you are hoping for).
There is some magic that needs to happen in the meantime. A process that will take your salty cabbage and transform it into something greater. We will cover that in the next post!