Piperine gives black pepper its bite. It acts on the same heat receptor as capsaicin, far more weakly, and slowly loses its pungency when ground pepper is exposed to light.
What it isยถ
Piperine is the alkaloid responsible for the pungency of black-pepper, the dried fruit of the vine Piper nigrum. It is a pale yellow crystalline solid, nearly insoluble in water and soluble in alcohol and oils. Black pepper typically contains a few per cent of piperine by weight โ commonly quoted figures run from about 2% to 9%, depending on variety, origin and processing. It is also the main pungent compound in white-pepper and long-pepper; cubeb, a relative, gets its bite mostly from other compounds.
Piperine was isolated in 1819 by the Danish physicist and chemist Hans Christian รrsted, better known for discovering that electric currents create magnetic fields.
How it worksยถ
๐ฌ Two receptors
Piperine activates TRPV1, the heat receptor that capsaicin targets, and also TRPA1, the receptor for mustard-oils. It is much less potent at TRPV1 than capsaicin โ pure piperine is rated at roughly 100,000 Scoville heat units, around a hundredth of capsaicin โ and pepper contains it in modest amounts, so the result is a quick, sharp prickle rather than a lasting burn.
The difference in character between pepper heat and chilli heat is partly about dose and partly about the molecules. Pepper's bite arrives fast and fades within a minute or so; chilli heat builds and lingers. Pepper also brings a large dose of aroma, which chilli powder often lacks, so the sensation reads as "peppery" rather than simply "hot".
Light and the fading of pepperยถ
Piperine is the trans,trans form of its molecule. Light, especially ultraviolet, converts it slowly into its isomers โ chavicine, isopiperine and isochavicine โ which are markedly less pungent. This is one reason ground pepper in a clear shaker on a sunny shelf tastes of little after a few months, and another reason to buy whole peppercorns and grind them as needed.
The other reason is aroma. Pepper's smell comes from volatile terpenes โ pinene, sabinene, limonene, ฮฒ-caryophyllene โ and from the sesquiterpene rotundone, which gives a distinctly woody, peppery note and is also found in some Syrah wines. These escape quickly once the peppercorn is cracked. Piperine is not volatile, so old pepper often keeps some bite while losing its perfume.
๐ก Keep pepper in the dark
Whole peppercorns in an opaque, airtight container keep well for a year or more. Ground pepper is best within a few weeks. A pepper mill is the simplest answer; see also storing-spices.
Black, white, green and longยถ
| Pepper | Processing | Effect on flavour |
|---|---|---|
| Black | Unripe berries dried whole; skin darkens | Piperine plus the most aroma, much of it in the skin |
| White | Ripe berries soaked, skin removed | Piperine remains, much of the skin's aroma lost; soaking can add a farmyard note |
| Green | Unripe berries preserved in brine or freeze-dried | Fresher, milder, more herbal |
| Long | Whole flower spikes of Piper longum, dried | Similar piperine bite, sweeter and more resinous |
Pink peppercorns are not related to pepper at all and contain no piperine. sichuan-pepper is also unrelated; its effect comes from sanshool. grains-of-paradise get their pungency from different compounds, gingerol-like ketones such as 6-paradol.
Piperine in the kitchenยถ
Because piperine is fat-soluble, pepper's bite dissolves into butter and oil. This is part of why a pepper sauce made with cream tastes rounder than pepper sprinkled on a dry steak, and why cooks add pepper to fat at the start of cacio e pepe, where it is toasted briefly before the pasta water goes in (see fat-and-flavour).
Long cooking does not destroy piperine, but it drives off pepper's aroma. That explains the old advice to add pepper late or at the table: the bite will survive a stew, the fragrance will not.
Piperine and curcuminยถ
Piperine is well known for slowing the body's breakdown of some other compounds. It inhibits enzymes in the gut wall and liver that attach glucuronic acid to molecules to speed their excretion. A frequently cited 1998 study found that giving piperine alongside curcumin, the colour compound of turmeric, greatly increased the amount of curcumin that reached the blood. This is why many turmeric supplements contain black pepper extract.
โ ๏ธ Not only curcumin
The same mechanism can affect how the body handles some medicines. Culinary amounts of pepper are not a concern for most people, but concentrated piperine supplements are a different dose altogether, and anyone taking prescription drugs should ask a pharmacist before taking them. herbsandspices.food makes no claims about health benefits of either compound.
Historyยถ
Pepper's bite made it the most traded spice in history; see pepper-in-history and the-spice-trade. Its chemistry was among the first of any spice to be studied: รrsted's isolation came within a few years of the first extraction of capsaicin, and piperine's structure was established later in the 19th century.