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Eat Cultured: The Art of Fermentation

written by Tim

Fermentation is an ancient art - but often forgotten in present days. Historians have traced signs of fermentation in food and beverage preparation dating as far back as 7000 BC. However, in modern times it’s not used as often anymore. Reasons include that people find it hard, are intimidated by or don't understand the process of fermentation. Instead, factory ingredients such as active yeast and vinegar have taken it’s place. Why? They are often quicker and cheaper! But trust me, fermentation is an art that doesn’t take long to master (and is affordable!). Before we get into the ins and outs of fermentation, let's get a quick overview about the mechanisms that make fermentation work.

How does fermentation work?

Fermentation is a metabolic process in which an organism converts a carbohydrate, such as starch or sugar (glucose) into acid, alcohol or gasses. Fermentation can only happen when there is an absence of oxygen in the process. There are some organisms that can perform fermentation themselves. Most common are bacteria, yeasts and muscle cells.

Three forms of fermentation

Ethanol/alcoholic fermentation

Yeast breaks down starches or sugars to energy, which is released as carbon dioxide. The resultant by-product is called ethanol (also known as alcohol). Beer and wine are great examples of this process!

Lactic acid fermentation

Yeast strains, bacteria and muscle cells convert starches or sugars into lactic acid. When we talk about fermenting food, most of the time we talk about lactic acid fermentation. The rest of the article is about this process.

Acetic acid fermentation

Acetic acid bacteria break down sugar and starches into a sour tasting vinegar. Different kinds of grains and fruit can be fermented into vinegar. Apple cider, rice and balsamic are well known acetic acid fermented products.

Fermentation is easier than you think!

To ferment you don’t need mind-boggling biological formulas or anything complicated you might not understand. You only have to take the oxygen away. This can be done with just tap water and salt. How? Water helps create an airtight environment when the product is covered and completely immersed. Additionally, salt helps with several things: it keeps the food crispy and preserves the structure. It also helps protect against unwanted bacteria that could potentially ruin the process.

The mix of water and salt is called brine. For your brine you want to have a good ratio, meaning that 1.5% to 5% of the brine has to be salt. Personally, I usually use around 30-32 grams of salt per litre of water.

When you start fermenting you will see that the yeast and bacteria like a warmer environment, as opposed to being kept in the fridge where this process is close to zero. This means that room temperature is an excellent temperature for fermentation. Most food takes between 3 days up to a week to ferment. In the end, once you achieve your desired stage of fermentation, you just pop it in the fridge to stop the fermentation process and you can store it for many months.

Why you should do it:

There are three great reasons why (lactic acid) fermentation is one of those things you should be doing at home.

  1. Health benefits: Rich in probiotic bacteria, fermented foods are one of the healthiest things to eat. You're getting all the good probiotics, digestive enzymes, and healthy acids that kick start your overall wellness. These will help our guts to digest, absorb and assimilate the nutrition of the things we eat. The bacteria will also help boost your immune system.

  2. Taste: Lactic acid is known by most people because of yogurt. It has a sour aroma and a very deep flavour. It makes certain foods taste a lot stronger, and these tastes can’t be achieved with adding spices or herbs!

  3. Preservation: Because of the airtight environment and the wanted bacteria in your product, you can keep fermented food for months even years. Because fermenting is quick and easy to do and doesn't require expensive equipment up front or any specialty tools, it's also the most simple of preservation.

DIY fermentation at home

The only things you need to ferment are:

  • A container (mason jars are the most common to use!)

  • Brine (water and salt mix)

  • The vegetables you want to ferment, any vegetable can be used (see below for ideas!)

  • make sure to use fresh, and organic vegetables since you don't want any unwanted pesticides in your food. The finished product is only as good as your produce.

  • Room temperature


  • Clean the vegetable you chose or take the skin off. Cut the vegetable to the size you would like it to have. For instance, tomatoes cut in half, celery root in finger size sticks… You get the idea.

  • Make a brine mixture of water and salt (recommended: 30 grams salt to 1 litre of water)

  • Add the vegetables to your mason jar and fill the jar with water. Make sure all of the vegetables are covered well.

  • For a twist, if you want to try some different tastes you can add whole spices as well. Examples: star anise, black pepper, cinnamon sticks.

  • Make sure the jar is covered so no unwanted crawlers or dust can come in. For this you can use a clean tea towel or a cheese cloth.

  • Leave the lid open so gasses can come out! If you close the lid pressure will build up and could cause the jar to explode.

  • Leave the jar at room temperature for 3-10 days. This is up to you! A 3 day fermentation means there is a lot less activity. The longer you wait the stronger the flavour gets.

  • When you are done you can eat it right away, or store it in the fridge with the lid closed.

  • Make sure to use a clean fork to get your vegetables out to reduce the amount of unwanted bacteria.

Things to ferment

You can be creative and ferment any vegetable you like. Here are some examples of the food I ferment.

  • Lemons (use the fermented lemon zest to give a very nice flavour to Arabic dishes)

  • Celery root

  • Hot peppers (such as habanero’s to make my own aged hot sauce)

  • Kimchi (a little bit of a different technique is used to make kimchi, you don’t make a brine but use salt to extract water from the cabbage so it can sit in its own juices.

  • Sourdough (personally I find this one the hardest to ferment, I still haven’t been able to it right)

  • Tomatoes

  • Sauerkraut

  • Carrots and potatoes (to make a vegan cheesy sauce!)

Recipes and Sidenotes

In our blog post 5 ways to cook cabbage you can find an amazing Kimchi recipe made by chef Alexander Gershberg. Sauerkraut is a wonderful dish to get started with fermentation, it's super easy! Additionally, this colorful medley of fermented mixed pickles is great as a side for almost any dish.

Even if you don't feel like fermenting at home, grant the Oogstmarkt at the Noordplein in Rotterdam a visit to find CLARK Fermentation's stall there! But be warned, it's hard to choose from the amount of Kombucha, Kimchi, and Tempeh.

Honorable mention: During my travels I came across something that blew my mind: kishk al khameer, in English known as poor man’s cheese. This cheese originates in Syria and is also made in Lebanon. Poor man’s cheese is fermented bulgur wheat rolled into balls and preserved in oil. Find the recipe here!

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