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heat Capsaicinoid Stability During Cooking

Increase/decrease of capsaicinoid content during fermentation depends on the members of the fermentation consortium. There are bacteria that can break down capsaicin very efficiently. Here is a reference that describes the spontaneous fermentation of pepper mash (full text available by following the link):

Dynamics of Bioactive Compounds during Spontaneous Fermentation of Paste Obtained from Capsicum ssp.-Stage towards a Product with Technological Application

Abstract: Six cultivars of chili (Cherry, Bulgarian Chilli, Cayenne, Fatalii, Habanero, and Carolina Reaper) from two species (Capsicum annuum and Capsicum chinense) have been studied. Anaerobic, spontaneous fermentation of pure chili paste was conducted for 21 days at 20 °C. The unfermented (UCP) and fermented chili pastes (FCP) were both subjected to physicochemical and microbiological characterization consisting of capsaicinoid, ascorbic acid, short-chain organic acids, phenolic compounds, and simple sugars analysis. Cell viability for Lactic Acid Bacteria (LAB) and Leuconostoc was determined before and after fermentation. Results indicate that capsaicinoids are very stable compounds, as notable differences between unfermented and fermented samples could not be seen. Carolina Reaper and Fatalii cultivars were amongst the most pungent, whereas Cherry, Cayenne, and Bulgarian types were low to moderate in pungency. Average loss of total ascorbic acid was 19.01%. Total phenolic compounds ranged between 36.89-195.43 mg/100 g for the fresh fruits and 35.60-180.40 mg/100 g for the fermented product. Losses through fermentation were not significant (p < 0.05). Plate counts indicated low initial numbers for LAB in the fresh samples, values ranging between 50-3700 CFU/g (colony-forming units). After fermentation, day 21, concentration of LAB (3.8 × 106-6.2 × 108 CFU/g) was high in all samples. Fermented chilies paste with enhanced biochemical and bacterial properties might further be used in the technology of vegetable (brining) or meat (curing) products, processes that generally involve the fermenting activity of different microorganisms, especially (LAB). Thus, the purpose of this research was the investigation of biochemical and microbial transformations that naturally occur in fermented chilies with a future perspective towards technological applications in cured meat products.

I feel like you buried the lead with that one... according to the study, fermentation INCREASED the heat of all the peppers tested by 20-50%!!!

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What??!! I really didn't expect that result - sure doesn't match my home saucing experience.

At least the first study result - that cooking reduces heat - jives with real life experience...

Curious what your source is on the bacteria species that break down capsaicin @ahayastani, I don't see any references to it in the linked study. Curious if somehow I'm encountering them in my own ferments since I swear I lose heat to fermentation.
You’re right, that does seem backwards… time and environmental exposure should degrade potency, as I understand it. I wonder if they fermented in a way which lost volume to evaporation, concentrating the result… need to see if they covered the fermentation methodology.

Edit: I don’t necessarily agree with their “more complete maceration” explanation, and it sounds like a guess to explain the counterintuitive result… I’d rather see a further study exploring it.

Further edit: like, if they’re implying they didn’t macerate their fresh samples enough to free statistically most of the capsaicinoids, then what were they bothering to measure? Maybe I misunderstand something.
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regarding the "more complete maceration" explanation:

3.2.2. Phenolic Compounds and Capsaicinoids Extraction​

Extraction of the compounds was made by adding 5 mL methanol + 1% HCl acid to 1 g of each sample. Samples were vortexed for one minute (Heidolph Reax), sonicated for 30 min (Elmasonic E 15 H), macerated for 24 h at 4 °C and centrifuged at 8000 rpm/10 min at room temperature (Eppendorf AG 5804, Hamburg, Germany). The supernatant was filtered (Chromafil Xtra nylon; 0.45 μm). 20 μL of each extract were injected in the HPLC system. Chromatograms were registered at λ = 280 nm for capsaicinoids and λ = 340 nm for phenolic compounds. Identification of capsaicinoids was made according to retention time, UV-Vis spectra and mass. Five concentrations of capsaicin standards (98.5% purity) were injected for capsaicinoid quantification.
I guess I should have read deeper and maybe I misrepresented the meaning of that excerpt somewhat when I said the heat increased after fermentation. I think the way the amount of capsaicin was calculated in the experiment was basically they first extracted the capsaicinoids out of the chile mash into methanol then ran their tests on that methanol extract... So in other words, I think basically they're saying fermentation probably affected how much of the capsaicinoids moved into that methanol solution out of the pepper mash itself - because it would be ludicrous to assume the actual total amount of capsaicinoids of the full system increased. ie just like if you grind coffee finer before brewing will get more caffeine in your finished coffee using the same beans - they're only saying fermentation of peppers probably lets the methanol "brewing" process have access to more capsaicinoids. At least I think that must be what they mean...

Yet the authors did make that comment about sauces being more pungent than peppers so seems like they still maybe think that this maceration effect is relevant beyond methanol extraction and is relevant to the actual heat experience, but no citation was given for that.
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I think we’ve all noticed the dramatic difference between eating a fresh pepper and eating a meal cooked with that same pepper: the meal is much milder and less physically irritating, even when large numbers of pods are used compared to eating just one raw pod. This effect seems larger than simple dilution would explain, so I looked deeper and found a study which partially answers the question.

Stability of Capsaicinoid Content at Raised Temperatures


All three tested capsaicinoids:
  • Higher temperatures resulted in more reduction than lower temperatures
  • Longer cooking results in more reduction than shorter, with most change happening within the first 15 minutes
  • Both low and high pH result in more reduction than neutral pH

Capsaicin and dihydrocapsaicin:
  • After 15 minutes, reduced by between ~60-75%

  • After 15 minutes, reduced by between ~95-100%

To remind ourselves of the burn profiles of these capsaicinoids:

Immediately, this makes me wonder how homodihydrocapsaicin is effected by cooking. A hypothesis could be that it is heavily reduced, like nordihydrocapsaicin is, and that this could explain the gulf in irritation between raw and cooked peppers: not just an overall reduction in capsaicinoids, but possibly a disproportionate reduction of the most irritating capsaicinoids. That said, of the three capsaicinoids studied above, the least irritating was the most reduced.
Thanks for sharing! I always wondered why fresh peppers have a different, more potent pain!