There is a pH Difference Between Fermented and Non Fermented Hot Sauce

I have recently experimented with fermenting hot peppers before making hot sauce to try and emulate some of the popular sauces that I enjoy. I also want to make a sauce that does not rely on vinegar for preservation and flavor. Some of the ingredients I use create an acidic environment or a low pH sauce that I can control by adding or subtracting different ingredients or substances. Fermenting peppers for hot sauce also makes a low pH environment.

How does fermentation effect the pH of a hot sauce?

The fermentation of hot peppers creates an acidic environment therefore lowering the pH level of the sauce and making it more acidic, similar to adding vinegar.  Fresh peppers will have a higher pH than fermented but will require preservatives and this will affect the pH of the hot sauce as well.

What is pH?

The pH is potential hydrogen and the reading on the pH scale is the calculated measurement of hydrogen ions in the substance that is getting measured, in this case fermented hot sauce. The lower the hydrogen ion concentration the more alkaline the sauce and so the higher the hydrogen ion, the more acidic. It is the acidity that helps with the preservation of the sauce and you want the results to be about 3.4 or you would otherwise need to use other methods of preservation.

Even though peppers are often classified as being low acid they generally fall below 7, with seven being neutral, on the pH scale.  However, most varieties of hot peppers will fall between the range of 4.9 to 6.1 and will fall lower on the scale if vinegar is added or they are fermented.


The best way to determine if fermentation effects the pH of a hot sauce is to make two identical batches of hot sauce, one fermented and one that is not and test each one once it is made into sauce. I use a pH meter but pH paper can be used and sauces can be sent to food labs as well. Read more on the top functioning meters on the Best pH Meters page. There could be some slight variables with the meter (and the ingredients if you do not measure accurately) but other than that it should be accurate.

Does fermenting change the pH of a hot sauce?

Yes! I prepared some of my most favorite peppers with a brine solution to be fermented for about a week. This is adequate time for the process because most of the fermentation happens in the first two weeks or less. I tested the brine solution with a pH meter everyday and below are the results. I typically open the top once a day to release the gasses so this is a normal process and should not affect the fermentation results that is being attempted.

Monday (day 1)6.01 pHTuesday (day 2)5.14 pHWednesday (day 3)4.48 pH
Thursday (day 4)3.64 pHFriday (day 5)3.28 pHSaturday (day 6)3.13 pH

The pH level radically decreased throughout the week for the first four days and then began to plateau or decreasing in smaller incremental amounts for the remainder of the week. The meter was calibrated before the test and cleaned after each use as it should be.

Day 1 – 6.01
Day 2 – 5.14
Day 3 – 4.48
Day 4 – 3.64
Day 5 – 3.28
Day 6 – 3.13

Fermented hot sauce has a lower pH than fresh hot sauce

I then made the peppers into a simple hot sauce recipe and tested the pH of the end results. That was compared to the same sauce using fresh ingredients. I would normally add vinegar to a hot sauce that uses fresh peppers but in this case I wanted to test the two process (fresh vs fermented) so I left it out until later. Ultimately the vinegar was added and I tested those results as well.

Here are the pH test results between the fermented and non-fermented hot sauce. The fermented hot sauce was significantly lower in pH than the non fermented. I used the same amount of peppers in each example and blended them both into a mash so that I was able to test them properly.

Fermented pH 3.35
Non Fermented pH 5.06

A hot sauce that has been fermented for 6 days will have almost 34% more acidity than a hot sauce that has not been fermented. I then added the exact same ingredients to each sauce and received similar reduced percentage of acidity but I did prefer the taste of the fermented sauce.

Enough with testing, how do they taste?

There is a fresh taste from the non-fermented sauce that I would expect from the jalapeno’s I love, and it has an enhanced tang due to the addition of vinegar. The fermented sauce also has a bite to it but has slightly less heat. Sauces can get tested at laboratories for the level of heat but this can be an expensive and time consuming process.

I don’t believe a taste test this to be a 100% scientific experiment but it will certainly provide an immediate reaction, especially if it is a flavor of sauce you consume often. I have noticed a sauce will “change” over time once it has been opened and exposed to air or in this case was never really sealed up. If you are performing this same test do it immediately to get the best results.

Fermenting reduces the heat of hot sauce

The fermentation process will change the level of heat in your hot sauce but it will also enhance the flavor of the peppers and retain the antioxidants. In an article published by titled Fermentation of Hot Sauce Juice Bacillus Licheniformis to Reduce Pungency the author Cho states that the after 5 days of fermentation the capsaicin in red and green peppers drastically decreased.  

It has also been my experience that any processing or preservation that is done to a hot pepper will diminish the amount of heat it retains. This includes cooking, smoking and freezing and some of these methods will remove valuable nutrients as well. The most heat you will get from a single hot pepper is at its freshest.

There are several things that you can do to reduce the heat of a hot pepper or hot sauce and this can be determined through testing. However, testing for the pH can easily be done with a pH meter or pH strips but testing for heat is not as easy. There is elaborate laboratory equipment available for your own “in lab” testing and there are handheld meters available as well. Both of these methods can be very expensive but if you are continually testing sauces for the level of heat it may be worth the investment.

The easiest way that I know to test the heat of a hot sauce is by taste test. If you are using a hot pepper that you use regularly to make hot sauce then you are probably sensitive to the amount of heat that it gives off. It is easy to determine the heat between different varieties of peppers but comparing two that have separate processes may be difficult.

The results of the experiment above determined that fermentation will lower the pH of a hot pepper and also reduce the amount of heat but are the two related? It is common belief that the hotter the peppers the more acid there is to it but this is not necessarily true.

pH is NOT related to the SHU of a hot pepper

There isn’t any research that points to the hotter the pepper the more acid it has to it. While it may seem logical, the pH is not related to where the pepper lands on the Scoville scale. There is much popular belief that the hotter the pepper the more acidity that it has but this is not true.

The “burn” that is felt is an actual pain from the level of capsaicin in the peppers. This pain does not leave physical scars and is not considered to be an acid and this includes the acidity in our stomachs. Studies have shown that capsaicin actually reduces heartburn and is not necessarily the cause.

It does not matter how hot a pepper is, the heat does not reflect the pH level

If hot peppers are fermented longer and they gradually lose their heat than they must become less acidic and have a lower pH right? Yes and No. The length of time that a sauce ferments has little to do with the overall heat or pH level at the end results. As state above the fermentation process happens within the first two weeks but fermenting longer will further enhance the flavor of the peppers at a very slow rate.

Here is what happens if you ferment longer

The fermentation process will never stop if the hot peppers are left in the same brine solution and the same atmospheric conditions. However, the process can slow down and may need equipment or facilities to ferment for long periods.

Our simple test above only measured over a period of six days and that is enough for the fermentation process to begin and perform the breakdown of sugars. The peppers will ferment “fully” in that period of time but the process continues and more complex flavors develop.

All peppers are acidic side of the pH scale but certain varieties of peppers will have a lower pH than others. Fermentation reduces the pH in a hot pepper to make a more acidic environment. There is a variance of the levels of pH between peppers varieties and even with those varieties.

If you are fermenting and want a less acidic sauce start with a pepper that is high on the pH scale and ferment for 5 to 7 days. This will allow the pepper to ferment and obtain intricate flavorings but will also reduce the acidic environment, although not by much.

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