As mentioned above, the main process that give Kimchi its distinctive taste and flavour is lacto-fermentation. When people think of fermentation, they usually think of beer and wine which is fermented using yeast. Lacto-fermentation is not carried out by yeast but by a strain of bacteria called lactobacillium. Under anaerobic circumstances (no oxygen), they convert sugars into lactic acid, giving them Kimchi its sour taste. The increase in lactic acid also means a reduction of pH which is extremely important as it prevents the growth of some of the most deadly bacteria such as Clostridium botulinum which causes Botulism that can kill you in a few hours. Because of this lacto-fermented products are one of the easiest and safest to make. This also includes sauerkraut.

When people think of the term lacto-fermentation, the sugar than comes to mind is lactose, the disaccharide sugar composed of a single galactose and glucose molecule bound together found in dairy products.  This being said, lacto-fermentation does not only work on lactose, but any kind of sugar. In order to start lacto-fermentation, you first want to kill of other bacteria before creating an anaerobic environment. When making Kimchi, this is done by first rubbing the Kimchi in salt and soaking it in brine to kill of other bacteria through osmotic creation. The salt also draws out water from the Kimchi, thus flooding the jar the Kimchi is made in with water, removing space for oxygen to build up and creating an anaerobic environment.

The salting of kimchi is also extremely important in terms of taste and texture. For one, the lack of water in the cabbage hardens a protein called pectin that occurs naturally in the cell wall of most fruit and vegetables. This gives the cabbage in the kimchi a nice crispy texture, preventing the cabbage from going soggy and limp.

For my take on Kimchi, I believe the best secret addition to an incredible Kimchi are freshly shucked oysters! By adding oysters to Kimchi, you add a dimension of flavour to the Kimchi. Kimchi made with oysters has the very refreshing smell of the ocean that makes you feel like you’re basking on the sandy beach on a sunny day. That, added to the salty punch provided by the oyster’s juices and supple mouth feel the oysters contributes to the Kimchi makes it worth the additional cost. From what I could find, fresh oysters used to be added tobaechu-kimchi before the cost of adding oysters became so high that people stopped adding it. This, coupled with the fact that most people started buying commercially made Kimchi, which didn’t have oysters added to keep the cost low, meant that adding oysters to Kimchi became a thing of the past. If you are unable to find fresh oysters to shuck and add to your kimchi, a much cheaper and more viable alternative is using frozen oysters. I personally have tried using canned oysters and honestly it was not worth it as it does not contribute any flavour at all.

In terms of safety, after a lot of painstaking research, fresh oysters are actually safe to add to Kimchi and this same Kimchi can be kept for many months without going bad. The most important factor be careful of is that the oysters must be submerged under the Kimchi brine. So here is the reasoning behind it. Most oysters in the first place are eaten raw, so just by themselves they are safe to eat. In a normal scenario, you would eat a raw oyster after its been opened for more than a few hours. However when added to Kimchi, the lactobacteria in the Kimchi prevent other types of bacteria from developing, thus protecting the oyster and keeping it safe to eat. The juice of the oysters also have an extremely high salt content, which helps to salt and preserve the Kimchi. After a few days, the oysters themselves will also start to ferment, changing their flavour.

There are also Kimchi recipes that include prawns and fish, but for safety reasons these recipes require you to ferment the Kimchi for up to a month before it is safe to eat as unless the prawns and fish are sashimi grade, they will only be safe to eat after fermenting for a longer period of time, compared to the normal 1 day.

Tongbaechu-kimchi 통배추김치

• Cabbage Preparation
  • 3kg of Napa Cabbages (배추), which is about 6 medium-sized ones
  • 400g of Fine Sea Salt
  • 2.5 litres of water
• Vegetables
  • 200g of Carrots
  • 400g of Korean Radish/Daikon/Mooli
  • 150g of Green Onions
  • 150g Asian Chives (부추)/Garlic Chives/More Green Onions
  • 150g Water Dropwort (미나리)
• Porridge
  • 500ml of Water
  • 30g Sugar
  • 60g of Glutinous Rice Flour/Potato Flour
  • 150g of Garlic Cloves
  • 40g of Ginger
  • 200g of Yellow or White Onions
  • 70g to 150g Korean Hot Pepper Flakes (고추가루), depending on how spicy you want it
  • 200ml of Fish Sauce
  • 150g of Fermented Salted Shrimp (새우젓) or Dried Sakura Shrimp
  • 40 Freshly Shucked Oysters
• To finish
  • Black and White Sesame Seeds

1. Gives the Napa cabbages a wash in water to remove any dirt and soil.
2. Cut the cabbages cross-section-wise, each into 4 evenly sliced parts, removing some of the root and core at the end. Using your hands, roughly separate the cabbage layers from each other.
3. Dissolve the salt in the water and add all the cabbages into the water, mixing together so that the salt water coats each leaf and stem. Try to submerge as much of the cabbage as possible.
4. Leave to soak from 1 to 2 hours, mixing every 30 minutes so that the cabbage gets evenly salted.
5. After salting, wash the cabbage thoroughly and drain off the water. The cabbage does not need to be totally dry.
6. While salting the cabbage, start preparing the vegetables by julienning the carrots and radishes into matchstick size pieces. Then, finely chop up the green onions, chives and water dropwort. Mix together and set aside.
7. Mince the garlic cloves and ginger and dice the onions.
8. Make the ‘porridge’ by dissolving the glutinous rice flour and sugar in the water before slowly bringing the mixture up to a boil.
9. Stir constantly to prevent the flour from burning and be ready to take the saucepan off the heat the moment the mixture starts to solidify as this occurs rather suddenly.
10. Once the mixture has become a paste, add in the fish sauce, minced garlic gloves, minced ginger and diced onions, fermented salted shrimp and hot pepper flakes. Mix well.
11. Add in the rest of the vegetables as well as the shucked oysters into the porridge and continue to mix.
12. Add the salted cabbages into the porridge, using your hands to coat the cabbages with the porridge well. This is a very important step.
13. Finish with a sprinkle of black and white sesame seeds before packing into three 2 litre jars. Do not fill the jars up to the brim and leave space for the kimchi to expand overnight.
14. Leave the jars out of the fridge overnight or longer with the lid closed to ferment.
15. After each day of fermentation, use a fork to press out the air from the kimchi before storing into the fridge.

Notes:

• Kimchi is made by lacto-fermentation, whereby simple sugars are converted to lactic acid by Lactobacillum in an anaerobic environment (an environment with no oxygen)
• The increase in levels of lactic acid lowers the pH value of the kimchi, giving it its classic sour taste. The low pH value combined with an anaerobic environment means that other dangerous bacteria such a botulism are unable to grow there, making kimchi extremely safe to make.
• Fresh oysters can be safely added to kimchi and eaten straight away in the same way that you would eat a freshly shucked oyster. After a few months however, it is still safe to eat kimchi with oysters as the environment created by the lactobacillum keeps the oyster safe from other bacteria. This is also aided by the salty brine that comes with the oyster. One important issue to note here is that to keep the oysters in this protective environment, the oysters must be kept submerged in the kimchi brine.
• Kimchi recipes that incorporate other seafood also exist but require up to a month’s fermentation time before being safe to eat and therefore I do not recommend them. The reason why kimchi with added oysters do not require as long a fermentation is because oysters can be eaten raw originally.
• You can replace fresh oysters with frozen oysters but not canned oysters as canned oysters no longer contribute flavour to the kimchi.
• Salting the kimchi is important for two reason:
  1. It kills of other bacteria present on the cabbage, allowing the good bacteria (lactobacillium) to grow.
  2. It hardens a plant protein called pectin that occurs in the cell walls of the plants, giving the kimchi its characteristic crispy texture, preventing the kimchi from going soggy and limp.
• One day of fermentation is enough for my kimchi to ferment enough for my taste but if you would like your kimchi to be stronger, feel free to ferment for longer. The average temperature where I live is 24°C (75°F).
• Placing the kimchi in the fridge does not slow it down but greatly reduces the rate of fermentation. I personally enjoy tasting the kimchi slowly over time as its taste evolves.
• Traditional kimchi is made using whole cabbages of halved cabbages. In my recipe I have decided to cut up the cabbage to make packing the jar and eating the kimchi more hassle free. I have tested using whole cabbages and have not found any variation in taste.
• As the stems are thicker than the leaves, it helps to add more salt on the stems.
• The porridge is extremely important in kimchi as due to its vicious nature, it is able to stick to the cabbage and infuse the cabbage with the taste of the herbs and spices.
• I store my kimchi is several 2 litre kilner jars but it is possible to buy specialised fermentation jars that have built-in air-release valves. I prefer kilner jars over these jars as they prevent the whole fridge from smelling of kimchi.
• After a period of fermentation, be careful when opening your jars as the kimchi is liable to explode due to the build up of carbon dioxide generated by fermentation.
• Because of this, I recommend not filling up the entire jar with kimchi, and opening the jars once a day when fermenting out of the fridge. When the kimchi is stored in the fridge, the fermentation slows to a point where you no longer have to release the gas.
• Wearing gloves is advisable when mixing the porridge with the cabbage as the hot pepper flakes might sting.
• In this recipe I dissolve the cabbage in a salt water solution compared to dry salting the cabbages. * I prefer this method as it keeps the cabbages slightly more moist, which means your kimchi will have more brine compared to a dry salting method.
• I cut of some part of the root of each cabbage as I feel this may be too hard to eat.
• It is possible to use any dried shrimp if you can’t find fermented shrimp as this is added only for the flavour.
• The word kimchi is actually a general term for any Korean dish made from salted vegetables, whether fermented or not. However, the Tonbaechu-kimchi variety is so famous that this is what people usually mean when they say kimchi.

It is also possible to buy specially made containers to store your kimchi, such as jars with in build air-release valves which release the carbon dioxide when the pressure builds up to high. When using normal jars, be careful when you seal the lid, as the pressure that builds up is sometimes enough to cause the jar to explode, especially when opening the lid. I personally just use normal 2 litre Kilner jars and release the air carefully after the first day of fermentation. After placing the kimchi in the fridge, I only release the air once every fortnight The main problem with using other vessels in my opinion is that the fridge will start to smell of kimchi, which is why some Korean families have specialised Kimchi fridges. If you are extremely enthusiast about making Kimchi, you could also buy an Onggi (옹기) which are traditional Korean earthenware pots used for fermentation.