Dihydrocapsaicin
Also written DHC
Quick answer
The second of the two compounds that make a chilli hot: capsaicin with one double bond removed, present in every hot pepper beside it and, in some, the larger share of the heat.
What it does
Dihydrocapsaicin and capsaicin are the two most abundant and most potent of the capsaicinoids, the family of compounds responsible for the heat of chillies; three lesser relatives, nordihydrocapsaicin, homocapsaicin and homodihydrocapsaicin, generally add little. Capsaicin is usually reported as the more abundant, at about equal parts with dihydrocapsaicin in Capsicum annuum and about two to one in C. frutescens. It is not always so. In the dried green fruit of seven Mexican C. annuum types, dihydrocapsaicin was 41 to 57 per cent of all the capsaicinoids and exceeded capsaicin in six of the seven: by a little in jalapeño and de árbol, by more than two to one in serrano and ancho, and by more than three to one in guajillo. Only chiltepín held more capsaicin, and narrowly.
How it behaves when cooked
Four properties of the molecule, and what they mean at the stove.
- Volatility
- low
- Fat solubility
- high
- Water solubility
- low
- Heat stability
- moderate
The only difference between the two molecules is one carbon–carbon double bond in the fatty tail, which capsaicin has and dihydrocapsaicin lacks: C18H29NO3 against C18H27NO3, two hydrogen atoms more. The four levels given here follow from that near-identity and were not separately measured in anything read for this profile; the computed measure of how strongly a compound prefers fat to water is, if anything, a little higher for dihydrocapsaicin than for capsaicin. For the cook this means there is nothing to do differently. What is said of capsaicin — that it stays in the pot, moves into fat and not into water, and is carried off the tongue by dairy and oil — is said of the two together, because the two arrive together in every hot chilli. It also means that a pungency figure calculated from laboratory analysis is a sum: in the study read here, heat was worked out from the measured capsaicinoids, and in most of the chillies analysed dihydrocapsaicin was the larger part of that sum.
Spices that carry it
Recorded on the compound rather than on each spice, so the two cannot disagree.
Measured at 45% of the capsaicinoids in dried green fruit, a little ahead of capsaicin at 37%.
The one type of seven in which capsaicin led, and narrowly: 48% capsaicin to 42% dihydrocapsaicin in dried green fruit.
In dried green jalapeño it was the largest single capsaicinoid measured, 45% of the total against 38% for capsaicin.
The highest share measured among seven Mexican types: 57% of the capsaicinoids in dried green serrano, more than twice the capsaicin.
Measured at 41% of the capsaicinoids in dried green fruit of the ancho type, against 15% for capsaicin.
In dried green fruit it was 42% of a small total, more than three times the capsaicin measured beside it.
What cooking and processing were measured to do to it
Findings from studies in which this compound was followed through heat, fat, water, drying or storage. Each belongs to its study and its conditions.
Drying · Decreases Capsaicin, Dihydrocapsaicin, pungency
Every drying method lowered the capsaicin and dihydrocapsaicin content of chilli below that of the fresh fruit, and in every method the higher temperature lost more. The smallest loss, about 13 per cent, followed freeze-drying at 40 °C; the largest, about 45 per cent, followed hot air with 100 W of microwaves at 60 °C. Freeze-drying and vacuum drying did not differ significantly and kept the most.
Conditions: 40 and 60 °C · Freeze-drying, vacuum, hot air, and hot air with 50 or 100 W of microwaves
What this does not show: One cultivar, halved and deseeded, so that the inner tissue was exposed to the drying air. It conflicts with studies of whole pods in which hotter, faster drying left more capsaicinoid than slow drying; the material and the range of temperatures differ.
Measured on the spice
Drying · Depends on conditions Capsaicin, Capsanthin, Dihydrocapsaicin, pungency, colour
Whole chillies of two Guizhou varieties held significantly more capsaicin and dihydrocapsaicin after hot-air drying at 75 °C for 12 h than after five days in the sun or twelve days in the shade; the highest content, 1.71 mg/g, was in hot-air-dried Xianjiao. Capsanthin followed the same order, highest after hot air and lowest after shade-drying. The authors attribute the result to time: the slow methods leave enzymes active and oxidation running for days.
Conditions: in air · Hot air at 75 °C; sun at 25 to 33 °C; shade at 18 to 25 °C · 12 h; about 5 days; about 12 days · Two Guizhou varieties, whole fruit dried to about 7 per cent moisture
For a whole chilli, the long exposure of slow drying can cost more pigment and pungency than the heat of a quick one.
What this does not show: One season and three treatments that differ in several ways at once. The same study found shade-drying gave the richer aroma profile, so the ranking depends on what is valued. Conflicts with the finding on halved chillies that higher temperature lost more capsaicinoid.
Measured on the spice
Not to be confused with
Compounds a reader is likely to take for this one, and why they differ.
Capsaicin
The same molecule but for one double bond, made by the same plant. “Capsaicin” on a label or in a recipe nearly always means both, and an analysis that reports capsaicin alone has left out what may be half the heat or more.
Questions this page answers
- what is dihydrocapsaicin
- dihydrocapsaicin vs capsaicin