An analysis of compounds in chilli peppers has revealed chemicals that seem to negate their heat-giving capsaicinoids. This explains why the Scoville scale for measuring spicyness isn’t always accurate, and could eventually lead to the development of an “anti-spice” condiment
By Chris Simms
14 May 2025
Piri piri or African bird’s eye chilli peppers
Steidi/Alamy
Accidentally made your food too spicy? One day, you might be able to reach for an “anti-spice” condiment to tame the heat of a dish, thanks to the discovery of chemicals found in chilli peppers that counteract their spicy sensation.
A chilli’s heat comes from compounds called capsaicinoids, which bind to receptors on nerve fibres within your mouth, sending impulses to the brain that create a burning sensation similar to those caused by a fire’s heat or a sting.
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Chilli aficionados compare the heat of different strains using the Scoville scale, which is based on the concentration of capsaicinoids, yet some varieties aren’t quite as hot as their Scoville rating suggests they should be. To investigate, Devin Peterson at the Ohio State University and his colleagues used an analytical method known as liquid chromatography-mass spectrometry to determine how much of two capsaicinoids – capsaicin and dihydrocapsaicin – were in powdered samples of 10 types of peppers, including chile de árbol, African bird’s eye and Scotch bonnet.
Then they gave samples of tomato juice containing powder from the different chillis to a panel of tasters. Each contained the same amount of capsaicin and dihydrocapsaicin – which should have been enough to give all the samples a relatively mild kick of 800 Scoville units.
But the tasters perceived the heat from the 10 peppers as different, so Peterson and his colleagues performed additional chemical analyses. This identified three compounds in the chilli powder – capsianoside I, roseoside and gingerglycolipid A – that were present in high quantities in the chillies that weren’t as intense as they should have been according to the Scoville scale. All three compounds are glucosides, molecules that contain the sugar glucose.