Introductory guide: Home fermentation

A Beginner's Guide for Home fermentation

This is a small guide so you can get started with home fermentation. We start with an introduction to understand fermentation, we will tell you how to make our first 10 ferments and there are also some lists of food, times and temperatures of fermentation of these ferments. 


Fermentation is a transformation of food by yeasts and bacteria that makes our food healthier, more digestible and nutritious. It is also a food preservation technique. In a much summarized way, fermented foods:

  • Improve the digestibility of food by breaking down some antinutrients and removing toxins and metals from aliments.
  • Improve the nutritional quality of food by making some new vitamins, minerals and enzymes that are not found in the original food.
  • Strengthen the immune systemreduce inflammation of the digestive system and prevent certain gastrointestinal pathologies, due to their contribution of probiotics to our flora.

Fermentation enriches our diet with new flavors and textures, rather acidic and crunchy, with recipes and preparations that are very easy to make at home.

Fermenting microorganisms need to break down sugar in a process called glycolysis to get the energy they need to live. But not all microorganisms obtain energy in the same way. There are 3 predominant types of fermentation in the kitchen:

  • Lactic fermentation of lactobacilli in yogurt, kefir, cheese and sauerkraut.
  • Alcoholic fermentation of Saccharomyces cerevisiae in wine, beer, bread, cocoa...
  • Acetic fermentation of acetobacter in kombucha and vinegar.

Depending on the fermenting microorganisms present in the food, one of those fermentations or another will predominate.

Conditions for fermentation

To make a good fermentation we must have our ferments in optimal conditions. But these conditions are different for each fermented food. In general, you should know that:

  • The 4 involved factors are: microorganisms, their food, temperature and time.
  • Warm temperatures speeds up fermentation and cold temperatures slow it down. Microorganisms die in extreme temperatures.
  • You should ferment at constant temperatures and in a dark ambient.
  • Protect your ferments from dust, insects and microorganisms unrelated to the main fermentation.
  • Salt protects lactic fermentations, but too much salt slows down fermentation. Salt also adds a crunchy and flavorful texture to your ferments.
  • Acetic fermentations need oxygen, whereas lactic and alcoholic fermentations do not.

What and why ferment?

  • Legumes to degrade phytates and increase their nutritional contribution, we ferment it while soaking.
  • Vegetables to increase their vitamins, antioxidants and amino acids, to preserve them and make them probiotic.
  • Sugary liquids to create natural carbonated drinks, with probiotics, without sugar, of any flavor and with more or less alcohol.
  • Cereals to degrade their antinutrients (phytic acid, lectins, enzyme inhibitors and gluten) and improve their nutritional intake.
  • Milk to reduce or eliminate lactose by transforming it into lactic acid, to preserve it and to make it probiotic.
  • Meat and fish to increase their contribution of organic acids, vitamins, peptides and fatty acids and to preserve food throughout the year.

Your pet closet

Each ferment has its own ideal temperature and time conditions. In general, they will ferment well in your pantry or in a fresh, dry and dark cupboard, covered with a cloth to protect them from external agents or a closed with a tap with a system that allows the gases of fermentation to be expelled, called air trap, but all that depends on each fermentation.

Keep always your ferments close to you to observe them often, do you go to know them better and feed them more easily.

Ferments have communities of living microorganisms that need to be fed frequently. If you do not feed them correctly, it is very easy for them to weaken, become contaminated or die. Once they are contaminated they cannot be recovered, you must start over with new and sterilized material.

If you are going to start home fermentation, make fermentations that adapt to your needs. For example, if you do not have much time, opt for sauerkraut or make kombucha before milk or water kefir, since they require less time.

Types of Fermentation

Controlled Culture: We expose the food to a culture that we already know and  have, so that the food ferments with the microorganisms of the culture that we add. For example:

  • Kombucha: we start the fermentation with some kombucha and the scoby from the previous batch.
  • Yogurt: we start the fermentation with a tablespoon of yogurt from the previous batch.

Wild Culture: We expose the food to microorganisms that live in the air or on the outside of the food itself. For example:

  • Sourdough: we start the fermentation with the microorganisms from the air and from the cereal shell. 
  • Wine: we start the fermentation with the microorganisms from the grape skin.

Fermentation Safety

It’s important to know the characteristics of each ferment, their individual needs and the elements of their environment. In general, keep in mind that:

  • To extreme the hygiene helps to avoid contamination, get familiar with the sterilization and the good cleaning of the pots and jars.
  • The bubbles are a good indication of the start, intensity and the end of the fermentation. The higher fermentation activity, the more bubbles it makes.
  • The room temperature, the acidity of the ferment and the salt will protect your ferments from microorganism contamination.
  • Fermented foods are acidic and non stainless steel metals react with the acidity. Non stainless steel metals can be in contact with the ferment for a moment but better don't use them for long time fermentations.
  • If your ferment has a strange smell, color or taste or something makes you doubt about its health, throw it away, sterilize the jar and the instruments you have used and… Start over!

Tips and tricks

Tap water contains chlorine that kills microorganisms. Let it sit overnight or make it boil it for 13 minutes before using it in your ferments to take out chlorine from tap water. You can also use bottled and spring water or sea water for the brines.

The jars and pots must be very clean although not always sterilized. If you use the same bottle continuously for the same ferment, clean it very well and you can rinse it with vinegar instead of sterilizing it.

Use preferably glass or stainless steel containers, as they are stable and inert materials. Other metals will react with the acidity of the fermented food, so it is not good to keep them in contact with your ferments for a long time. You can use non stainless steel tools if it is only for a moment, for example to straining, stirring, etc. Put a cloth between the metal lid of the container and the fermented food so the metal will not react with the acidity.

Fermentation generates gas.

If you cover the jar tightly it can explode! If you are afraid of that use plastic jars for short fermentations that generate gas. As glass is much more stable it is better to use glass containers at long fermentations, but plastic bottles will inflate first and will help you to recognize the fermenting cycles.

Use an air trap to release the pressure inside a closed container and to avoid possible contaminations, you can buy or manufacture it at home. A punctured balloon instead of the bottle cap is a good substitute, it will inflate and little by little it will release the fermentation gas. If you don't have an air trap, you can always open and close the jar at the same time that the gas forms, to release it. 

If your vegetables lose water during fermentation add more water, if you add more brine it may be too salty when you eat them. If vegetables are in contact with the air for several days they become dry and they will easily contaminated.

Microorganisms die at some extreme temperatures. Do not boil them! Put your clean finger in their food: temperature will be safe for them if you can keep the finger there for at least 10 seconds without burning. The cold slows down and stops the fermentation. It will never be the same to ferment in winter than in summer, so there is no an exact recipe to ferment, practice to know the correct way to ferment in your conditions.

Feed your ferments with as natural and least modified products as possible. Keep in mind the food that each microorganism needs, for example, milk kefir with vegetable milk will not work, since the microorganisms in milk kefir eat lactose, or a kombucha with stevia instead of sugar will not work, since sucrose is the food of the microorganisms in kombucha. 

My first 10 ferments

Bread sourdough

Always use whole wheat flour as it has more yeast and now you are about to “hunt” yeasts and bacteria from the environment to grow them in your sourdough. Strength flour, bran, natural yeasts of the fruit and regular sugar (sucrose) help to develop the sourdough. Always use the same amount of flour and water, following these steps:

  • Day 1: Mix whole wheat flour and water. Stir and cover it with a cloth. Let it rest in the dark and at room temperature.
  • Day 2: Add whole wheat flour, water, and a pinch of sugar, organic fruits with natural yeasts or organic bran.
  • Day 3: You may already have bubbles and a more acidic smell. Repeat the process from day 3.
  • Day 4: Maybe there is liquid on the surface. Repeat the process from day 3.
  • Day 5: Put some dough in a glass of water. If it floats, you can use it to ferment your bread. Repeat the process from day 3.

There are many ways to make sourdough; on the internet you will find several recipes. At cold temperatures it will need more days and at warm temperatures it will activate quickly. This process can take between 3 and 12 days. If you want to know more about sourdough, visit our article "Sourdough Biology" and if you already have your sourdough ready to make bread there is another article about "Make sourdough bread at home ".


Wash the cabbage and reserve the outer leaves. Remove the hard part and chop the inner leaves into very fine pieces.

Add 15 grams or a tablespoon of salt per kilo of cabbage, stir and let it rest for an hour, until it begins to release juice. Massage the chopped cabbage for about 10-15 minutes until at squeezing a handful it releases its own juice.

Put the chopped cabbage well-pressed in a sterilized container and dip it in its own juice. Add the reserved leaves on top of the chopped cabbage as a lid to keep the ferment submerged. Cover the jar and store it cool, at about 18 degrees.

You will need to open and close the pot once or twice a day for about 4 weeks to release the gas from the fermentation. At first it will make more bubbles and over time it will make less. You can start eating it after 7 days, the longer it is, the more fermented it will be.

At 4 weeks or when it no longer releases gas, store the bottle in a fresh or cool place closed with a metal cap, if the metal is not in contact with the sauerkraut, or with a plastic cap. It is safely kept for at least one year. In the article Making sauerkraut at home there is a more extensive explanation. 


You can ferment vegetables chopped in their juice, like with sauerkraut, or whole or cut and fermented in brine. The chunks can be larger or smaller, depending on the vegetable, and the fermentation will be faster with a larger contact surface between the brine and the vegetable.

Prepare the brine with between 2% and 3% salt per liter of water. Add more salt if you live in a hot and humid climate to better protection of the ferment. Ferment the cucumbers with a 5% brine to make them crispier.

The fermentation process of vegetables is similar to the fermentation of sauerkraut. We can do it by chopping, salting and pressing to release its juice, or directly ferment in chopped or whole with brine that we have previously made.

Brine the whole or chunky vegetable in a sterilized container, press the vegetable pieces against itself so that they does not float, and, optionally, put something that keeps the vegetables submerged in the brine, the same way we use the external leaves of the cabbage to keep the sauerkraut submerged.

Open and close the jar often to burp the gas and when it is no longer fermentation close it tight and store it in a cool and fresh place. It last for a year... or more!


Yogurt needs heat to ferment, so it is most practical to use a yogurt maker. If you don't have one, you can replace it with an express pot, although with the pot the temperature will not be so well controlled, so it is possible that you get a more liquid and less acid yogurt.

Put a tablespoon of yogurt in sterilized glasses and fill them with milk, stir them, cover them and put them to ferment for 8 hours in the yogurt maker. If you are going to use the pressure cooker, the milk in the glasses must be a bit warm, but not too warm so you not kill the microorganisms.

If you don't have a yogurt maker, heat the pressure cooker by boiling water in it and then discard the water. Quickly insert the filled and covered glasses into the pot (without water but hot) and cover it as quickly as possible, trying to keep all the heat. Wrap the pot in a blanket and leave it for 8 hours in a place without ventilation, where it does not lose heat, such as the oven. But the oven should be off!

8 hours later, remove the glasses from the yogurt maker or pressure cooker and let them cool. If you get a liquid yogurt, it is because the lacking of temperature or because the initial culture was poor, try whit another natural yogurt and try to keep the temperature warmer while fermenting. 

Store the yogurts in the fridge and consume them for the next 10 days. When you have 1 yogurt left, use it to repeat the process, although every 2 or 3 times you will have to buy a new yogurt from the store, otherway the culture will not be strong enough to make a good fermentation.

Milk kefir

To prepare milk kefir first you must find the kefir grains, which is the culture you need to ferment milk in this way. They are sold and given away online. Put 2 or 3 tablespoons of kefir grains for each liter (0,22 gallons) of animal and whole milk. Cover the jar with a cloth or paper and a rubber band or a string.

Leave it fermenting for a day at room temperature to obtain the kefir milk drink. Before drinking the kefir milk, strain it to extract the kefir grains to be able to prepare the next batch with them.

If you leave it longer it will curdle and the whey will separate from the milk. It's okay! You can make spreadable cheese by separating the kefir grains and squeezing all the whey out of the curdled milk with a filter cloth or a coffee filter. Put some salt and species on the cheese paste and let it rest overnight in the fridge. You can drink the leftover whey, use it to soak legumes, incorporate it into your bread and pastry recipes, make probiotic shakes, marinate meat...

To prepare the next batch clean and rinse the bottle with water, do not wash the kefir grains with water, if you want, wash them with fresh milk and start over.

Water kefir

To prepare water kefir you need to get the tibicos culture. They are sold and given away online. Put 3 or 4 tablespoons of tibicos for each liter (0,22 gallons) of water, add 40 grams of sugar or panela and some sweet fruits, make your own tests and find a way to make it to your liking.

Cover the jar with a cloth or a paper, put a rubber band or a cord and leave it to ferment for two or three days at room temperature, then strain the result to extract the tibicos and use them in the next batch. You can now drink your kefir water or store it in the fridge.

You can also make a second fermentation of the kefir water, this time without the tibicos, adding other flavors of fruits, herbs, roots... to the water to obtain a bubbled and varied drink. Do the second fermentation in a hermetically sealed jar for another day or two at room temperature. Be very careful: the bubbles from the second fermentation can make the jar explode! If you are afraid of that use a plastic container for this second fermentation. It will inflate before to explode.

The tibicos and the milk kefir grains will grow and reproduce in each batch. If you have too much grains you can give them away, eat them raw, make smoothies, ice creams... Or give it to your healthy animals, they love them!


To make Kombucha you need the initial culture, called scoby and some starter tea, which is the fermented kombucha ready to drink. It is also sold and given away online.

If your jar is 1 gallon, make a tea with 2 teaspoons of white, green or black tea, of the Camellia sinensis specie, in 14 cups of water, add 1 cup of sugar and stir. Infuse for 10 to 60 minutes, to your liking.

Let cold the tea and put it in a wide-mouthed jar and add 2 cups of fermented kombucha and the Scoby, always with the cold tea, or you will kill the microorganisms! Cover the jar with a cloth or paper and let it ferment at a temperature between 21 and 26 degrees.

Taste your kombucha from day 5 to day 12. When it is to your liking, put the Scoby aside and save a part of the drink to start the next batch. When you handle the Scoby you can do it with your hands, well cleaned and rinsed with a little diluted vinegar.

Drink the rest or do a second fermentation in a hermetically closed jar for 2 or 3 days adding fruits, herbs, roots... whatever you want, to obtain a drink with more bubbles and a different flavor. Be careful: the bubbles from the second fermentation can make the jar explode! If you are afraid of that use a plastic container for this second fermentation. It will inflate before to explode.


Get grapes, or another fruit, such as blackberry or raspberry, as natural as possible so that it has a lot of yeast on its surface. Mash it and remove the fibrous parts, as they can give a bitter taste to the wine.

Let the juice with the fruit skin rest at about 18 or 20 degrees in a jar covered with a cloth, so that insects do not enter and observe how it begins to bubble.

Once or twice a day remove and push the floating parts to the bottom so that they are not in contact with the air for long time. The fermentation of the wine does not require much oxygen, so if the pieces of fruit are in contact with oxygen for several days, they can become contaminated and that will spoil the wine.

From time to time taste the wine. In about 15 days it will have lost its sweetness and you will have your wine ready. Decant the wine and bottle it so that it is not in contact with oxygen, so that it does not transform into vinegar.

Store the bottles in a cold environment, because if it is hot and not all the sugar in the fruit has been consumed, it can continue fermenting and you may end up with a sparkling wine and / or an exploded bottle.

Every year we make our own wine from our 250 to 300 vines. There the article that shows “The process of making wine at home”.


You can make fruit vinegar by making a 3% to 9% alcohol wine. The more alcohol the wine has you will get more acidic vinegar and it will be softer if the wine has less alcohol.

Let the fruit wine rest in a wide-mouthed container with some space for the air and covered with a cloth. A large surface area of ​​the wine in contact with the air and with good ventilation will aid in oxidation, which is necessary for acetic fermentation.

You can use some of your old vinegar or organic vinegar to start the fermentation, but usually it is not necessary.

When it starts to ferment you will see bubbles and over time a mother may or may not form, that does not matter. You can use the mother in your next vinegar fermentation, but it is not necessary.

You should let it ferment from 1 to 6 months, tasting from time to time until you like it. Store in tightly closed narrow neck bottles that avoid contact with air, that way it will not continue fermenting.

Garlic fermented in honey

Fill a very clean jar with peeled and crushed garlic cloves and add raw honey to coat the garlic. Store it in a cool, dark place. The honey has to be raw so that it provides the necessary microorganisms and enzymes for fermentation.

Wait a month, until the garlic absorbs the color and flavor of the honey. Check and stir the garlic every little bit, at the beginning check it every day and some days later check it with les frequency, until it stops fermenting.

During fermentation you must open and close the pot to expel the gas and you will see that the honey will be watered down by the moisture of the garlic. About a month later it will stop fermenting, depending on the ambient temperature.

When the fermentation stops, you can keep it tightly closed in your pantry to take it at any time. After 6 months the garlic is sweet!

Take the garlic in the morning and / or use the honey as syrup. Start taking them before the cold season, it will help you to prevent colds, flus and winter coughs, as it strengths the immune system. You can add more garlic and more honey while you are consuming it.

If you want to know moner about to have a hive at home, you can read the article "A hive at home: raw honey and other products".

Temperatures and Times:

  • Sourdough: Keep at 25-30ºC (77–86 F) for 4 or 6 hours, until it doubles in volume. If it floats in water it can already be used to make bread.
  • Sauerkraut: Keep at 18 - 21ºC (64-69 F) for 1 to 4 weeks. Store in the fridge and consume it in the following year.
  • Vegetables: Keep at 18 - 21ºC (64-69 F) for 1 to 4 weeks. Store in the fridge and consume it in the following year.
  • Yogurt: Keep at 40 - 45ºC (104-8113 F) for 6 to 8 hours. Store in the fridge and consume in the next 10 days.
  • Milk kefir: Keep at 18 - 20ºC (64-68 F) for 24 hours. Store in the fridge and consume in the next 15 days.
  • Water kefir: Keep at 18 - 20ºC (64-68 F) for 48 hours. Make a second fermentation of 1 or 2 days, optionally. Store in the fridge and consume in the following months.
  • Kombucha: Keep at 21 - 26ºC (69-77) for 7 to 12 days. Make a second fermentation for 2 to 4 days, optionally. Store in the fridge and consume in the following weeks.
  • Vinegar: Keep it at room temperature, depending on it, fermentation can last from a few to 6 months. Store in oxygen-free containers at room temperature.
  • Wine: Keep at about 18ºC (64F) for about 2 weeks, until the bubbling stops. Bottle it and keep it in a fresh and cool place. Consume it in the following months.
  • Garlic in honey: Keep at room temperature for at least one month. Keep in a cool place and consume indefinitely, refilling the jar with new honey and garlic.

Proportions and times:

  • Sourdough: 1:1:1 ratio: 50 g of sourdough, 50 ml of water and 50 g of flour. Feed it when it has a lot of bubbles.
  • Sauerkraut: 15 grams or 1 tablespoon of salt per 1 kg of cabbage. Open and close it every day for 1.
  • Vegetables: Brine them in 2 to 3%. Open and close every day for 1 month.
  • Yogurt: One tablespoon of natural or Greek yogurt for each glass and 6 to 8 hours in heat.
  • Milk kefir: 2 to 3 tablespoons of kefir grain per liter (0,22 Gallon) of whole and animal milk. New batch every 24 to 36 hours.
  • Waterkefir: 2 to 3 tablespoons of tibics, 5 of sugar and some fruit per liter (0,22 Gallon) of non-chloride water. New batch every 36 to 48 hours.
  • Kombucha: For 1 gallon: 2 teaspoons of Camellia sinensis tea, 1 cup of sugar, 14 cups of water and 2 cups of kombucha as a starter of the new batch tea, check it from day 5 to day 12.

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