How Long Hot Peppers Can Be Fermented

Written by Michael Grant in General Fermentation Topics,Lacto Fermented Vegetables

Three Jars of Fermented Peppers

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Hot peppers are a fun and interesting fruit to ferment.  They come in a wide variety of shapes, sizes and temperature ratings.  The amount of sugar found in the fruit is the real determination of how long something will ferment.  The more sugars which are available the longer the fermentation can last (within reason).

Peppers will ferment for 14-60 days depending on the type of pepper and the environmental conditions.  Conditions which affect fermentation time include the method used, temperature and the availability of sugar and oxygen.

When discussing hot peppers we seldom consider the amount of sugar in the pepper itself rather we focus on the amount of capsaicin found in the pepper but when it comes to fermentation time the amount of sugar is the important thing to know.

100 grams of jalapenos have a sugar content of 4.1 grams with a Scoville Heat Units (SHU) between 2500 – 5000 whereas 100 grams of cayenne peppers contain 10.0 grams of sugar with a SHU between 30,000 – 50,000.  Here is a chart showing the sugar content of a sample of hot peppers and the SHU range of each.

TypeSugar ContentScoville Heat Units 
Carolina Reaper5.3 grams2,000,000 – 2,200,000
Ghost pepper3.1 grams855,000 – 1,463,000
Habanero5.3 grams350,000 – 855,000
Scotch bonnet5.3 grams100,000 – 350,000
Thai hot peppers4.4 grams50,000 – 100,000
Cayenne10.0 grams30,000 – 50,000
Serrano 3.3 grams5,000 – 15,000
Jalapenos4.1 grams2,500 – 5,000
Anaheim 4.4 grams1,000 – 1,500

Once the active fermentation is complete the peppers will continue to change in flavor and texture.  This is due to the chemical compounds in the peppers reacting with one another and the sides of the container.  Some hot peppers are aged in wooden barrels for 3 – 5 years before they are made into sauce.  This ageing process allows the peppers’ flavor to change even though the fermentation process is complete after a month or two.

How long should peppers ferment?

This is like asking how long to cook a steak.  If you are making hot sauce you may want to ferment your peppers for a month or two.  If you want pickled Jalapenos then they will pickle in two to three weeks.  For a deep complex flavored hot sauce you can ferment your peppers for years.  

The length of time peppers should be fermented is determined by the desired end product and the pepper’s sugar content.  Fresh tasting hot sauce with a sharp flavor and higher amounts of capsaicin can be fermented in a week.  Longer aged peppers are less hot, less sweet with a more complex flavor.

Once the easily fermentable sugar has been consumed the fermentation process will slow down and essentially stop.  Once this happens the fermentation stage is complete and the maturation stage will begin.  This is where the esters and organic acids produced by the fermentation process will begin to react with one another and with the compounds which remain from the original peppers.

A long aging process mellows the flavors and gives the fermented peppers a chance to develop a flavor and texture quite different from the young ferment.  It is similar to the changes which occur in wine as it ages.

How to tell when your peppers have finished fermenting

Fermentation is a word which means to boil due to the active bubbles which are created as carbon dioxide is produced while something is actively fermenting.  This active fermentation continues as long as there is fuel for the various microorganisms to consume.  Fuels which are used in fermentation include simple sugars and alcohols which can be used by the yeast, lactic acid bacteria and acetic acid bacteria.  

The pressure method 

The pressure method is done by placing the peppers into a sealed environment and leaving them for a day or two to determine if the fermentation is still producing carbon dioxide.  Once there is not perceptible pressure buildup the peppers have finished active fermentation.

  1. Place the peppers into a sealable container and place the lid
  2. Place the container in a cool location out of direct light
  3. After 24 hours burp the lid. 
  4. If there is any pressure buildup or bubbles rising from the peppers they are still fermenting
  5. If there is no buildup, place the lid and leave it for two or three days before checking again
  6. Once you have reached a week without any pressure buildup the peppers have finished active fermentation 
  7. Place them into the fridge and consume at your leisure

The pH method

This method requires the use of pH strips or some other pH testing equipment.  They can be found in hardware stores for testing pool chemical pH.  With this method you are not testing to determine if the fermentation is complete instead whether it has a low enough pH to protect the peppers from spoilage bacteria.  Once a pH of 4.0 has been reached you can slow the fermentation down through refrigeration.

  1. Open the jar and dip the pH strip or probe into the liquid  
  2. Check the color of the pH strip 
  3. If it corresponds with a pH of less than 4.0 the peppers can safely be stored
  4. If it is still higher than 4.0, ferment the peppers another few days and check again.

A pH less than 4.6 produces an environment which inhibits the growth of unwanted spoilage bacteria so to be safe ensure the peppers have a pH lower than 4.5 (I like 4.0 to be extra cautious).  Once a low pH has been achieved the peppers will last a long time in the fridge.  Once in the fridge the fermentation process will slow so the production of carbon dioxide will slow and essentially stop.

The Taste test method

This is the least reliable method for long term storage but it is great for fermenting peppers which are going to be used quickly.  Although the peppers may not be fully fermented if they are going to be used within a short period of time, storing them in the fridge will ensure they will last a month without worry.

  1. After a week or so of fermentation taste a pepper
  2. If it has reached a level of tang you like place them in the fridge
  3. If not, ferment them another few days.

Peppers tested this way need to be consumed quickly so only make enough for a month or two and check for mold growth each time you use them. 

How do you know when fermented peppers are bad?

The great thing about fermenting vegetables of all types is that it is a very safe method of preserving food for long time storage.  The fermentation process prevents unwanted spoilage and harmful bacteria from growing in the food but this does not mean that they will last forever or the fermentation process is infallible.

Fermented peppers that have gone bad have a distinctive off smell and may have mold growth on its surface.  The peppers will take on a mushy texture and may form large amounts of sediment on the bottom of the container.  The pH will also begin to rise as spoilage bacteria begin to dominate.

Do not consume peppers which have mold spots.  Mold will be growing on the surface of the container or peppers, will have a fuzzy look and send ‘roots’ into the peppers.  Not all mold is harmful or produces unpleasant flavors but don’t take the chance and pitch any container which has mold growth.

Can you ferment peppers without salt?

Salt is used in lacto fermentation to prevent the growth of unwanted bacteria, yeast and mold which can alter the flavor of the final product.  Lactic acid bacteria are highly salt tolerant whereas most other bacteria found on peppers (and other fruits and vegetables) are not salt tolerant.

Peppers can be fermented without salt to produce vinegar using acetic acid bacteria and yeast.  The vinegar will have varying amounts of capsaicin depending on the type of pepper used and the amount of sugar used to produce the vinegar.

The end product here is not the peppers themselves but the liquid which the peppers have been fermented in.  You can use any type of peppers.  Each type has a unique flavor and heat profile.

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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