Chili pepper burn and thickness perception in soups
What it found
In 47 people in the Netherlands, capsaicin made soups taste less easy to tell apart by thickness.
The effect was the same whether people ate chili often or rarely.
What they found
Studies in people
Thickness harder to tell
Thickness discrimination thresholds rose from 11.3 mPas with no capsaicin to 16.1 mPas at 1 ppm and 21.4 mPas at 10 ppm. That is a 42% increase at 1 ppm and an 89% increase at 10 ppm.
Same for both methods
Thresholds went up similarly whether capsaicin was mixed into the soup or used as a mouth rinse before tasting. The pre-rinse raised thresholds by 40% at 1 ppm and 87% at 10 ppm.
Chili habit made no difference
People who ate chili often and people who ate it rarely showed no significant difference in thickness discrimination thresholds. This was true for both the soup mixture and the pre-rinse.
Burn and liking
Frequent chili eaters reported lower burn intensity and liked the spicy soups more than infrequent eaters. At 10 ppm, frequent eaters on average liked the soup while infrequent eaters disliked it.
Viscosity did not change burn
Soups that differed in thickness but had the same capsaicin level were rated the same for burn. The authors say the viscosity differences were too small to affect burn.
What the authors conclude
“We conclude that oral burn caused by capsaicin affects thickness discrimination independently of reported chili pepper intake.”
Also in their conclusions
- They conclude that oral burn caused by capsaicin affects thickness discrimination independently of reported chili pepper intake.
- They suggest the ability of capsaicin to alter thickness discrimination may be due to increased neural noise, attentional effects or cross-modal interactions.
How it was done
The trigeminal nerve carries both chemical irritation and texture sensations, so the authors wanted to know whether the burn of capsaicin changes how well people can tell liquid foods apart by thickness.
Forty-seven adults in the Netherlands tasted chicken bouillon soups thickened with xanthan gum, with capsaicin at 0, 1 or 10 ppm added to the soup or held in the mouth as a pre-rinse. They rated burn and liking, and thickness discrimination thresholds were measured with a forced-choice staircase method.
What it can’t tell you
- All participants were young Caucasian adults in the Netherlands, so the findings may not apply to other groups.
- The study did not include people who avoid spicy foods or people from countries with very high chili intake.
- The authors note their study may not have had enough people to detect a difference in thickness thresholds between infrequent and frequent chili eaters.
Who paid
- Authors work at
- Wageningen University, the Netherlands; The Pennsylvania State University, USA
The paper
- Title
- Capsaicin burn increases thickness discrimination thresholds independently of chronic chili intake
- Type
- Study
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Lyu C, Schijvens D, Hayes JE, Stieger M (2021). Capsaicin burn increases thickness discrimination thresholds independently of chronic chili intake. Food research international (Ottawa, Ont.). doi:10.1016/j.foodres.2021.110702Free full textPubMed 34600694DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error