Is the heat in chilli seeds?
No. Chilli heat is made in the placenta, the pale ribs and core that hold the seeds. Seeds taste hot only because they sit against the placenta and pick up capsaicin from it. To make a chilli milder, cut out the placenta and ribs along with the seeds. In super-hot varieties the fruit wall also makes capsaicin.
Checked October 20, 2026 · How we source facts
Where the heat is made
Chilli heat comes from capsaicinoids, compounds made in glands or vesicles on the fruit's placenta [2]. The placenta is the tissue that holds the seeds [1].
Plant scientists report that capsaicinoids build up mainly in the surface cells of the septa, the internal ribs that connect the placenta to the fruit wall [3]. They are secreted into small cavities under the surface that swell into blisters [3].
Why the seeds seem hot
Guinness World Records calls the belief that seeds carry the heat a common misconception: the capsaicin is contained in the placenta [1]. New Mexico State University chilli breeders say seeds are not the source of heat, but they can touch the capsaicinoids because they sit so close to the placenta [2].
In a 2007 tissue analysis, capsaicinoids were absent from the seeds themselves, and small amounts found in earlier studies were attributed to surface contamination [3]. The same paper notes that blisters on the ribs can contaminate nearby seeds when the fruit is handled roughly [3].
Super-hots are different
Most chillies, including jalapenos, make capsaicinoids only in vesicles on the placenta [4]. Researchers at New Mexico State University found that super-hot varieties, above 1 million Scoville heat units, also grow capsaicinoid vesicles on the fruit wall [4].
That extra source helps explain their extreme heat [4], and it means the flesh of a super-hot carries heat of its own [4].
How to make a chilli milder
Extension food-safety guides say that removing the seeds and the placenta decreases the heat [5], and that a recipe's heat can be adjusted by removing some or all of the seeds and membranes [6]. Heat also varies from fruit to fruit with genetics, weather, growing conditions and the age of the fruit [2].
What doesn’t work
- Removing only the seeds and leaving the ribs: the heat is made in the placenta and ribs, not the seeds [1][2][3].
- Expecting seed removal to tame a super-hot: their fruit walls also make capsaicinoids [4].
- Judging heat by variety alone: genetics, weather, growing conditions and fruit age all change capsaicin content [2].
Questions
Are chilli seeds spicy at all?
Seeds are not the source of heat. A 2007 analysis found no capsaicinoids in the seeds themselves; they can pick up capsaicin from the nearby placenta.
What is the placenta in a chilli?
It is the tissue that holds the seeds, and it is where the glands that produce capsaicinoids are found.
What should I remove to make a chilli milder?
Remove the seeds and the placenta, including the membranes or ribs.
Why are super-hot chillies so hot?
Besides the placenta, super-hots grow capsaicinoid vesicles on the fruit wall, which leads to extremely high Scoville ratings.
Which is the hottest chilli?
As of its 2023 record, Guinness World Records listed Pepper X, averaging 2,693,000 Scoville heat units, as the hottest chilli pepper.
More guides
Sources
- Guinness World Records (archived 19 Sep 2024): Seeds-carry-heat is a misconception; capsaicin is in the placenta, the tissue that holds the seeds; Pepper X 2,693,000 SHU (23 Aug 2023).
- New Mexico State University, Circular 706 (Coon, Walker, Lozada, Guzman & Bosland, 2023): Capsaicinoids produced in glands or vesicles on the placenta; seeds not the source but contact capsaicinoids; genetics, weather, growing conditions, fruit age affect heat.
- Stewart et al., Journal of Experimental Botany 58(5):979-991 (2007): Capsaicinoids accumulate in epidermal cells of the interlocular septa, secreted into subcuticular cavities that become blisters; absent from seeds; seeds can be contaminated.
- Bosland, Coon & Cooke, J. Amer. Soc. Hort. Sci. 140(3):253-256 (2015): Most chillies make capsaicinoids only on the placenta; super-hots (>1 million SHU) also have vesicles on the pericarp (fruit wall).
- Colorado State University Extension (Food Smart Colorado): Placenta has the highest capsaicin concentration; remove seeds and placenta to decrease heat; wear gloves and glasses. (secondary source)
- Penn State Extension: Heat can be adjusted by removing seeds and/or membranes; wear gloves; wash hands with soap and water before touching your face. (secondary source)