Science of Kimchi





Introduction: Science of Kimchi

About: I am a student in 8th grade, I enjoy cooking, programming, 3-D design, photography, and nature!

Kimchi is one of the worlds healthiest probiotics, it is packed with vitamins and health microorganisms and it can be made right at home. In this Instructable, I will show you how to make easy, yummy and healthy kimchi, as well as talk about the complex science that makes it so beneficial and delectable!

Step 1: Ingredients and Equipment


  • 1 large head of Napa Cabbage
  • 1 cup Daikon Radish
  • 4 Green Onions
  • 1/4 Cup Sea Salt (non-iodized, I use Celtic sea salt)
  • 1-3 tablespoons Korean Chili Pepper; Gochugaru (3 tablespoons will be very spicy so I recommend starting with just one)
  • 1 tablespoon grated Garlic
  • 1 teaspoon grated Ginger
  • 1 teaspoon Sugar
  • Water (Try to use distilled or reverse osmosis water, water with fluoride or chlorine will prevent fermentation)

You can also add other veggies such as bok-choy, carrots, etc.


  • Cutting board and a Chef's Knife
  • Large mixing bowl
  • Small mixing bowl
  • Basic measuring utensils
  • Colander
  • Plate and a weight for soaking cabbage
  • Jar with a seal-able lid
  • Gloves - Optional to protect your hands when mixing

Step 2: Prepping the Cabbage

In order to make kimchi, the Napa cabbage must be soft and tender. The first step is to cut the cabbage, first into four quarters lengthwise and then into 1-2 inch strips crosswise, like pictured. Then place all the cabbage into the large mixing bowl and add the salt. Using gloves (if you want) mix the non-iodized salt into the cabbage until well mixed. Finally, add enough water to cover the top of the cabbage, then use the plate to cover the cabbage. You will want to add a weight to the plate and remove excess water as the cabbage sets, let sit for at least 1 hour.

Step 3: Combining the Spices

Once the cabbage is almost done soaking you can make your spice mixture. First, finely mince or grate the ginger and garlic, and add them to a small mixing bowl. Then pour in the Gochugaru and sugar and mix it. Finally, mix in the first two tablespoons of water, continue to add more until it forms a smooth, but not watery paste.

Step 4: Mixing Everything Together!

The next step is to mix everything together, but first, you need prep the other vegetables starting with the Daikon radish. Cut the radish into 2 inch long matchsticks until it fills at least one cup. Then cut the green onions into inch long pieces. Rinse and strain the cabbage in the colander, then add it back to the large mixing bowl without any water. Mix in the daikon radish and the green onions. Finally, add the seasoning paste and mix everything very well until all the cabbage is well coated.

Step 5: Fermentation and Refrigeration

The final step in the process is fermentation, which is what gives Kimchi its unique flavor. Once you have mixed everything, get a clean jar with a sealable lid. Pack the mixture into the jar leaving just under an inch at the top. It is very important to pack the kimchi down so the brine submerges all the vegetables. If the veggies are not fully submerged there is a chance mold could form. Also to have the best fermentation, make sure all air bubbles are removed. If you see an air bubble use your finger or a skewer to help the air escape.

Once all of this has been completed put the lid(s) on the jar(s). Let the kimchi sit at about 65°F for 1-5 days to ferment checking each day to pack the cabbage down, check for air bubbles, and tasting to see if it is fermented to your liking. If you are happy with it place it in the fridge for storage. You can enjoy it right away, or give it a weak for the best flavor!

Step 6: Conclusion - the Science

Kimchi, like yogurt and kombucha, is a very healthy probiotic, which is very good for digestion and kills bad bacteria. However, eating napa cabbage alone wouldn't do this, kimchi is so healthy because of the fermentation. It starts with the salt and cabbage which are the most important part of the process, by salting the cabbage it causes osmosis, which causes the cell structure to weaken which softens the cabbage. The cabbage once rinsed is mixed with all the other ingredients which are mostly just for flavor. Then the microorganisms take over, the most important is Lactobacillus Plantarum which helps give kimchi its unique flavor. Lactobacillus Plantarum from the salted cabbage which also causes most of the fermentation. Lactobacillus Plantarum thrives in warm, low oxygen environments which is why kimchi must me surrounded in brine in a sealed container and kept at about 65°F. Then, sugars begin to break down and metabolize creating lactic acid, decreasing pH. Kimchi in an ideal situation should have a pH around 4.5.

Kimchi, like all fermented foods, has a lot of science behind it. Changing any variable, the temperature, the time, the ingredients, can have a major impact on the outcome of the end product. So, if you decide to make kimchi, consider yourself a chef, but also a scientist.

If you wish to learn more here are a few resources I found that are reliable sources for more on the science and facts:



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    9 Questions

    In step 5 you say to make sure to pack it down and make sure it's covered in brine . Is the brine the salted water from the cabbage soak ?


    Yes it is just all the liquid that stayed in the cabbage.

    Is Napa Cabbage compulsory? Any substitutes like normal cabbage or iceberg lettuce?

    Also won't the rinsing remove all the nutrients (unless you use it to top up the jar, coz you have nowhere mentioned to store the brine when rinsing)?

    Kimchi is just the Korean term for a pickled vegetable side-dish. Traditionally it is done with nappa cabbage but also a host of other vegetables both leafy and crunchy. I have used normal cabbage before as well as daikon radish, currently I am making it with wild greens, you can do it with beans, seaweed...there are hundreds of varities of kimchi.

    1 more answer

    Oh great thanks, will try someday. We normally don't get radish here (India) in summer, but will definitely try once it is available.

    Your instructions say "Rinse and strain in the colander," but it's unclear what is in the colander getting rinsed & strained. It would seem from the preceding sentence that it's the green onions, though later I read "The cabbage once rinsed..." but can find no reference to rinsing the cabbage in your instructions. Could you please elucidate?


    Thank you for noticing this mistake I fixed it above, and yes it is the cabbage you want to rinse and strain.

    3 more answers



    Not the green onions

    I usually put my Napa in a ziplock and let it sit overnight...this gives a nice light saltiness, but also softens the cabbage nicely for texture...he means to rinse off all the salt brine...I usually rinse, then taste the Napa to check for saltiness, when to my liking I squeeze out the water and go to next process.


    First, I love kimchi and many thanks for your fine 'ible.

    Q: You said, "Filtered Water (Non-distilled water will prevent fermentation)"

    Which is it? Filtered (i.e. not distilled) water, or distilled water, as you say that non-distilled water prevents fermentation? Fermentation is what we're after here, right?


    What you want is water that doesn't contain fluoride, or chlorine in it, these prevent fermentation. Almost all distilled water is free of these, however, only some water filtration processes remove fluoride and chlorine them such as Reverse Osmosis. If you can use distilled, if not distilled use Reverse Osmosis or the next best-filtered water you can get.


    De onde surgem os microorganismos? Não seria necessario o acréscimo de algum fermento específico?


    Não, levedura em não é necessária a bactéria vem do repolho.

    Will this work if I omit the sugar? I have to be sugar-free.


    I recommend leaving the sugar, it is very little sugar and most is consumed by the bacteria in fermentation.

    1 more answer

    the sugar will be eaten up by the bacteria, it starts the fermentation process but is quickly consumed....then the bacteria works on vegies.


    What is the source of the bacteria, just found on the cabbage? In the air?

    usually small brined shrimp or dried shrimp is used in the paste, also fish sauce is is already fermented, so starts the process faster

    1 more answer


    The probiotic bacteria is found in and on the cabbage, this probiotic bacteria is known as Lactobacillus.


    Looks really cool, have you tried it yet? and did you include carrots, that would probably make it even better?

    We have already eaten the first bottle! A triple batch has been made now, minus the carrot. The carrot was nice, but not needed. The best Instructables are ones that you go back to repeatedly. Good job!

    I’m glad you liked it! Also, please consider posting in the “I made it” section above.

    Awesome recipe and beautiful photos! I hope you will post more and more! ;)

    Too bad they do not have a first time author contest going right now, your instructable is not only interesting but also very pretty. Well done.

    1 reply

    Thank you, I wish they did!!

    I must say that you explained on how to make kimchi amazing

    1 reply

    Thank you, I tried to make it as easy to follow as I could!

    in the contests, can you vote for the cucumber kimchi while I vote for you. Is it a deal?

    1 reply

    Maybe, however your recipe Is not yet in the contest.

    Can this be done in a vacuum seal bag (like used for sous vide)

    4 replies

    A by-product of the fermentation process is CO2 gas, which must have a means of escape. The author's recommendation of checking the kimchi each day will allow the accumulated gas to escape, but a sealed bag would not offer that opportunity. This is OK as long as you realize that the vacuum sealed bag will likely start to "inflate" as the CO2 is produced, although with this quantity of kimchi, not too much, and that you open the bag or refrigerate it to stop the fermentation prior to catastrophic failure of the bag.

    Also to note, when making kimchi it is recommended to check the kimchi daily, as mentioned above, so that will also be a problem with this method. I recommend just using a jar and you shouldn't have any problems. However, if you do attempt it with a bag though please comment about your experience!

    You could try to use a bag, however, a bag could break and leak, or it could contaminate the kimchi, so use very high quality bags!

    The wall of most true vacuum bags is 3-5mil. They won`t leak, and they won`t contaminate if you buy food grade brands (Costco for instance).

    Thanks, I appreciate your feedback!