How to Safely Ferment Peppers Without an Airlock


Fermented Jalapenos in a swing top jar

When you first start your fermenting peppers it can ba a little scary.  After all you are doing something which most people would consider unsanitary practices, leaving peppers out on the counter for extended periods of time, but if it is done properly it is perfectly safe and produces some of the best flavors in the world. 

In the beginning you may not have all the equipment which other fermentors have but do not let that stop you.  Fermentation has been practiced for thousands of years, with and without airlocks so don’t let that stop you.

To safely ferment peppers without an airlock in anaerobically keep the peppers under a 2-3% salt brine within a temperature range of 60-85℉ (15-30℃) in a clean container.  This will control the environment and encourage the growth of lactic acid bacteria.

There are several methods which can be used to keep your fermenting peppers safe from spoilage but all of them do the same thing: restrict the oxygen available to the bacteria and yeast.

Can you ferment peppers without an airlock?

Fermenting peppers without an airlock requires more attention to the process but is easily done. There are several methods which all have their own idiosyncrasies.  

Using mason or repurposed jars to ferment peppers

When fermenting in a mason jar or some other glass container which is not meant for holding pressure then the jar must be burped (opened slightly to let pressure out) regularly.  If this is not done then the pressure can build up enough to explode which can be dangerous and will make a big mess.

Use flip top jars to ferment peppers

These jars are my favorite method of fermenting vegetables.  They are tough with thick glass sides which can stand a fair amount of pressure.  The spring loaded lids with the rubber seals help prevent air from entering into the fermenting peppers while letting the pressure within the container escape if it gets too high.

This type of jar is not recommended for canning as the seals are not good enough to prevent air from entering into the vacuum produced by the canning process but they are great for fermentation as the pressure produced within the jar can escape without potential explosions while preventing air from getting back in.

The benefit of this is that the fermenting peppers will quickly consume any available oxygen in the container.  This prevents mold growth and encourages the growth of lactic acid bacteria and because the container does not need to be opened to release pressure preventing any oxygen from entering the jar.

It is important to test the seal of any jar you use when fermenting to ensure the lid makes a positive seal.  To do that fill the jar half full with water and turn the jar upside down and shake.  If water escapes from inside the jar it needs a new seal.

Use a vegetable fermentation crock to ferment peppers

There are many types of crock on the market which can be used to ferment vegetables.  They range from pickle jars which use weighted disks to hold the vegetables under the liquid to jars with water, a water seal which keeps the oxygen out of the jar.  

Fermentation crocks which use weights to hold the vegetables under the liquid brine are the most common types found in stores or second hand.  These are the hardest to use as they need constant care to ensure mold does not get out of hand during fermentation and storage.

Mold needs oxygen to grow, so the theory goes that if the food is held under the liquid where its access to oxygen is limited it will not grow.  It will grow unfortunately on the surface of the container where it has access to its food source (any carbohydrate) and oxygen.  To safely use these containers a higher amount of salt needs to be used, the surface of the liquid needs to be inspected regularly and any mold needs to be removed and the area cleaned.  If the mold is left too long it can send long “roots” into the food in search for more food.  This spoils the entire batch, can lead to sickness and will give the entire batch an off musty flavor.

Water sealed crocks have a trough at the top of the crock which the lid fits into.  When the crock is fermenting peppers the trough is meant to be filled with water.  This prevents air exchange between the environment and the inside of the crock but allows any built up pressure to be released.  This prevents the need to constantly check the fermentation during the required fermentation time. 

 To use these crocks properly fill them up to the top leaving only an inch or two of head room after the weights have been added.  Place the lid on the crock and add enough water to prevent air flow.  Check the water level regularly to ensure it does not dry up.  Once the fermentation period is up you can taste test the peppers easily by lifting the lid and removing one of the weights. 

Use a wooden barrel to ferment peppers without an airlock

Wooden barrels used to be the main way goods were shipped and stored worldwide.  They were cheap to manufacture, were durable and could be used for a variety of purposes.  This made them great containers for fermenting vegetables including peppers.

There are many benefits to using a wooden barrel for fermenting peppers:

  1. They are safer than using plastic containers
  2. They add additional flavor to the peppers
  3. They allow pressure to escape while preventing air exchange

What happens when peppers are fermented without an airlock

Airlocks are devices which allow one way flow of pressurized gas from inside a container out.  This prevents the introduction of oxygen into the container.  This prevents the growth of mold and other unwanted oxygen dependent organisms in the peppers.

Fermenting peppers without an airlock can be done in two ways, either in an airtight container or by aerobic fermentation.

What happens in an airtight fermenting container

When the container is airtight the fermentation produces CO2 gas which builds up within the container.  Once the pressure gets high enough it will cause failure in the container at its weakest point.  This could be the lid seal, a thin section of the container or a weakness in the wall of the container due to damage.  When this happens the container will violently disintegrate and send pieces of container and peppers flying.

This is why it is important to release pressure from the container while it ferments daily until fermentation slows.  Once it slows you can either burp the container occasionally or refrigerate it to slow any further fermentation.

What happens in a non-sealed fermenting container

These containers are like the standard crocks which can be found everywhere.  They have a lid which limits the free flow of air to a certain degree but as the temperature fluctuates air is exchanged into and out of the container.  This air exchange allows pressure within the container to escape, preventing pressure buildup and the associated damage it can cause but it also allows oxygen into the container which enables mold growth on the surface of the container.

Mold can grow in all sorts of environments including salty liquid, acidic conditions and a wide variety of temperatures.  This makes it hard to prevent its growth.  Its achilles heel is its dependence on oxygen.  

Mold is pervasive in the environment and cannot be destroyed in the home kitchen so it will be present in the container already and only needs oxygen and a food source to grow.  Unlike yeast and bacteria which can only utilize simple sugars for food energy, mold can use carbohydrates of all types including long chain starches which the structure of the peppers is made up of.

Mold will begin to grow on the surface of the container where it has access to oxygen and some type of food energy.  In time it will send tendrils down into the container in search of more food energy and it can also begin to produce spores which then begin to grow on the surface of the container spreading out as it grows.

This is why it is important to keep the peppers under the liquid when using this type of fermentation container and to regularly check the fermentation for signs of mold growth.

Does pepper fermentation need to be airtight?

There are many ways to ferment peppers which include aerobic and anaerobic methods (with and without oxygen).  Both of these methods do not use an airtight environment and in fact it is dangerous to ferment peppers this way.

It is not necessary to place peppers in an airtight container.  An airtight environment prevents air exchange from the container which is dangerous as the pressure in the container can build substantially and explode the container.  It is best to use one way airlocks to allow pressure escape.

When fermenting peppers it is important to use the method of fermentation which is appropriate for the end product. 

 When making pickled peppers an anaerobic environment is needed.  This is when an airlock is needed which allows carbon dioxide to escape from the container and prevents oxygen from the atmosphere from getting in.

If the end product is a vinegar then an aerobic environment is needed to allow the acetic acid bacteria to grow.  This will produce a two step fermentation where ambient yeasts will convert the sugars into alcohol which is then used to produce acetic acid (vinegar).  

How to ferment peppers in an aerobic environment

Fermenting peppers in an aerobic environment does not produce a pickle like ferment without oxygen but rather a liquid vinegar which can be very hot and flavorful.  Since peppers are a fruit they have a fair amount of sugar in them but they will need added sugar to produce vinegar with enough acetic acid to store well (for a hot pepper vinegar recipe click here).

The process is just like making any other fruit vinegar.  The yeast on the fruit and in the environment will ferment the sugar in the container which will then be converted into acetic acid by acetic acid bacteria.  The heat of the vinegar will depend on the type of pepper you used and if you removed the pith from the inside of the peppers.

Three ways to make a homemade airlock for fermenting peppers

If don’t have access to an airlocked fermentation container then you can easily make one using one of the following methods:

The cork and hose method

If you have a container with a cork lid you can easily make an airlock with a piece of hose and a bottle of water.  

  1. Drill a hole in the cork lid slightly smaller than the hose
  2. Jam the hose into the hole 
  3. Put the other end into the bottle 

To use this setup: 

  1. Fill the container with hot peppers and brine and place the lid
  2. Fill the bottle with enough water to cover the end of the hose

The pressure produced by the fermenting peppers will exit through the hose and create bubbles in the bottle but any air from the atmosphere will be prevented from entering the container by the water barrier.  

Make a mason jar airlock

Mason jars are one of the favorite fermentation jars due to their utility, sizes and price but they don’t fit the airlocks which are found at the local fermentation store.  They are meant for demijohns or larger carboys. 

To make a normal mason jar lid work as an airlock you will need:

  1. A standard metal mason jar lid which will fit your jar 
  2. A wine or beer fermentation airlock
  3. A ⅜” drill bit and drill
  4. A hot glue gun

instructions:

  1. Drill a hole in the center of the mason jar lid
  2. Jam the airlock into the hole
  3. Use the hot glue gun to seal the plastic airlock with the metal lid on both sides

When the glue is cooled you can use it on any mason jar of the right size.  When the lid starts to get old just heat the plastic up and pull the airlock out of the lid and insert it into a new one.

A plastic bag filled with water

This is the simplest method of making an airlock but it has its drawbacks.  The idea is that a plastic bag filled with water will take on the shape of the container which you are using and that is mostly true.  

When using a bag filled with water as an airlock be sure the bag is close to the size of the jar.  Too large and it will wrinkle and let air in and too small and it will not fill the surface of the container.  Also ensure it has no leaks otherwise the water will just leak into the ferment below diluting the brine and causing spoilage.

To use, fill the container leaving at least ⅓ of the container empty.  Place the bag into the container and fill it with clean water until it covers the fermentation by a few inches.  Smooth out any wrinkles along the sides and seal the bag.

Now as the fermentation produces carbon dioxide it will rise to the top and make its way along the bottom of the bag to the sides and escape. Any air will be blocked from entering the container.

Michael Grant

Mike has been an enthusiast of fermentation for over ten years. With humble beginnings of making kombucha for himself to the intricacies of making miso, vinegar and kefir. He makes a wide variety of fermented foods and drinks for his own consumption and family and friends. Being a serial learner he began experimenting with a wide variety of fermented products and learning widely from books, online from content and scientific studies about fermentation, its health benefits, how to use fermented food products in everyday life and the various techniques used to produce them both traditionally and commercially. With a focus on producing his own fermented products in an urban environment with little access to garden space he began Urban Fermentation to help others who want to get the benefits of fermentation in their lives. He provides a wide variety of content covering fermented drinks like kombucha and water kefir, milk kefir and yogurt, vinegar production and lacto-fermentation such as pickles, sauerkraut for those who have to rely on others for food production. With an insatiable hunger to know more about fermentation from all nations and cultures he also has learned to make natto, miso and soy sauce, with more to come as the body of knowledge about fermentation is constantly expanding and becoming more popular as time passes.

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