capsaicin

Every hot compound in this library is measured against one molecule. Capsaicin's receptor, TRPV1, is the one David Julius identified in 1997, work that won a share of the 2021 Nobel Prize in Physiology or Medicine, and capsaicin has been the benchmark ever since: piperine, the gingerols, and eugenol are all described on this site by how weakly or strongly they trip the same channel capsaicin trips hardest. In this library the molecule itself comes from chilies, fresh green and dried red, seasoning three recipes across two kitchens, always as a floor of warmth rather than a headline heat.

Capsaicin is C₁₈H₂₇NO₃, and its defining feature is not stability but geometry: it fits into a specific pocket of TRPV1 in a head-down, tail-up orientation, held there by hydrogen bonds to two amino acids, threonine 551 and glutamate 571, the same pocket ginger's own heat compounds bind in the same way. One measurement against the human channel puts capsaicin's half-maximal effective concentration at 9.8 nanomolar, the sharpest of the three compared in that study: [6]-shogaol needs 568 nanomolar and [6]-gingerol needs 2,399 to do the same job, roughly two hundred and fifty times more work for the same result. A separate measurement, comparing capsaicin against piperine, puts capsaicin closer to 290 nanomolar and piperine near 38,000: different assay, different baseline, but the same shape each time. Capsaicin is not more potent by a little, wherever it is measured against.

Capsaicin's own signal, in this library's citations, runs through TRPV1, the receptor Julius used it to identify in the first place. The recipes here use it sparingly and their own descriptions say so: two dried chilies diluted across four servings of a Japanese curry register as warmth in the chest rather than heat on the tongue, and fresh green chilies in a chicken and molokhiya broth read as a bright, grassy heat that cuts the richness without burying the greens. Three recipes, two kitchens, and in each one capsaicin is the floor the other spices stand on, not the feature.