Piperine
Also written piperin
Quick answer
The pungent alkaloid of black pepper — a slower, blunter, more quickly fading heat than capsaicin, produced by a different molecule that this catalogue therefore refuses to measure on the Scoville scale.
What it does
Piperine gives a pungency that arrives faster than capsaicin and leaves faster, sits further forward in the mouth, and carries a faint bitterness capsaicin does not have. It is very much weaker by weight — the reason a dish can be peppered heavily and a chilli of the same mass would be inedible. What people identify as the smell of black pepper is not piperine at all but the volatile terpenes around it, which is why pepper ground a week ago still bites and no longer smells of anything much.
How it works
The physiological account, where one is established.
Piperine acts on the same population of heat-and-irritation sensing nerve endings that capsaicin does, which is why the two sensations are recognisably of a kind despite the enormous difference in potency and the difference in structure. It is not a capsaicinoid and there is no conversion between them.
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
Piperine behaves like capsaicin in the pan and unlike it in the jar. It does not evaporate, so pepper does not lose its bite in storage or in a long braise, and it extracts into fat far better than into water. But it degrades slowly under sustained heat and light, which is one reason long-cooked dishes are often re-peppered at the end, and it isomerises on prolonged exposure to light into forms that are much less pungent. The practical rule that follows is the opposite of the one for chilli: pepper added at the start contributes body and pepper added at the end contributes bite and aroma, and a dish that wants both needs pepper twice.
Spices that carry it
Recorded on the compound rather than on each spice, so the two cannot disagree.
- Black pepperPrincipal component
- Long pepperPrincipal component
A different species carrying the same alkaloid, alongside a sweeter and more complex aromatic fraction that black pepper does not have.
- UzizaPrincipal component
The West African Piper, and the reason uziza is pungent rather than merely bitter. Same compound and same mechanism as black pepper, in a species that reached Europe by the Sahara routes rather than the Indian Ocean.
- White pepperPrincipal component
The same berry with the pericarp removed, so the piperine largely remains while much of the terpene aroma is lost — a hotter-seeming, less aromatic pepper from an identical fruit.
- Green peppercornMajor component
Picked unripe and preserved before the piperine content reaches its maximum, which is why green peppercorns taste fresh and herbal rather than sharply hot.
- CubebContributing component
Present at lower levels than in black pepper, and overtaken by the bitterness — which is why cubeb is a Piper with genuine piperine content that nobody uses for its pungency.
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.
Simmering and boiling · Decreases Piperine
Black pepper boiled for 10 or 20 min, or pressure cooked for 10 min, lost between 16 and 34 per cent of its piperine, with the largest loss in pressure cooking. The loss was somewhat lower when red gram was present.
Conditions: in water · Boiling for 10 or 20 min; pressure cooking for 10 min · Black pepper alone and with red gram or tamarind
What this does not show: Read in the abstract only. The abstract does not say whether the pepper was whole or ground, or what the piperine became. Pungency itself was not tasted.
Measured on the spice
Simmering and boiling · Decreases Piperine, Total extractable oleoresin, pungency
Both piperine and the total extractable oleoresin of black pepper declined on heating between 50 and 120 °C, and the decline followed first-order kinetics: a constant fraction of what remains is lost in each interval of time, faster at higher temperature. The same loss was followed in open-pan cooking, in pressure cooking and in a slow cooker.
Conditions: 50 to 120 °C held steady, and under changing temperature · Also followed in open-pan cooking, pressure cooking and a slow cooker
What this does not show: Read in the abstract only, which reports the form of the loss but no rate constants or percentages, so its size at any given temperature cannot be stated here.
Measured on the spice
Storage · Converts Piperine, Isopiperine, Chavicine, Isochavicine
Light converts piperine into its three geometric isomers: isopiperine, chavicine and isochavicine. Under fluorescent light, sunlight and ultraviolet the conversion increased with the intensity of the light and the time of exposure, then levelled off at a steady mixture. In four commercial ground black peppers the three isomers were all present, but in small amounts beside piperine: on the scale the authors used, piperine measured about 10 to 12, isochavicine 0.37 to 0.42, isopiperine 0.15 to 0.23 and chavicine 0.01 to 0.07.
Conditions: Fluorescent light, sunlight and 254 nm ultraviolet at varying intensity and exposure time
The isomerisation is real, but in the ground pepper these authors bought it had not gone far: piperine still greatly outweighed its isomers. Light is one route by which pepper can lose pungency, not proof that a given jar has.
What this does not show: Read in the abstract only. The kinetics were measured on the compounds under laboratory lamps, the abstract gives no rates, and it does not report the pungency of the isomers or the storage history of the four products.
Measured on the spice
Fermenting · Retains Piperine, 3-methylindole (skatole), volatile oil
Of 45 bacterial isolates taken from black pepper, seven removed the fruit wall of fresh berries almost completely (98 to 100 per cent) and of dried black pepper in part (over 60 per cent) within five days of immersion. They were identified by 16S rRNA sequencing as strains of Bacillus subtilis, Bacillus licheniformis, Acinetobacter baumannii, Klebsiella pneumoniae and Microbacterium barkeri, and were found to secrete cellulase, pectinase, amylase, protease and xylanase. The white pepper obtained was reported free of the off-odour compound skatole, with oleoresin, piperine and essential oil within the acceptable range and their constituents unaffected.
Conditions: in water · Within 5 days · Fresh ripe berries or dried black pepper immersed in a suspension of selected bacterial isolates
What this does not show: Read in the abstract only, which gives no piperine or oil figures. Work by the developers of the process, whose strains are patent deposits; two of the species named include strains that cause disease, and the abstract does not discuss that.
Measured on the spice
Drying · Retains Piperine, pungency, drying time
Fresh ripe Kampot pepper held 38.5 mg of piperine per gram. Oven drying at 55 or 65 °C, with or without boiling beforehand, did not change the piperine content significantly. The drying rate constant almost doubled between 55 and 65 °C, and after drying to constant mass the berries held about 0.02 kg of water per kilogram of dry matter whatever the conditions. The authors suggest piperine survives because it sits mostly in the inner core of the berry and not in the skin.
Conditions: in air · 55 or 65 °C · 8 h of monitored drying, then overnight to constant mass · Ripe red Kampot berries, with or without a boiling pretreatment
What this does not show: Two temperatures only, in a laboratory oven, on ripe red berries. Volatile oil was not measured, so the result says nothing about aroma.
Measured on the spice
Drying · Decreases Piperine, drying time, moisture
An ultrasound pretreatment before drying cut the drying time of black pepper from about 601 min in the control to about 445 min, a reduction of 26 per cent, or 19 per cent once the 40 min of pretreatment is counted. The dried pepper reached 9.6 per cent moisture and held 18.64 mg of piperine per gram of dry weight, a loss of about 6 per cent.
Conditions: Pretreatment at 50 °C · 40 min of ultrasound at 35 kHz before drying · Optimised by response surface methodology against an untreated control
What this does not show: Read in the abstract and conclusions only. An optimisation study at laboratory scale; volatile oil was not among the responses reported there.
Measured on the spice
Decontamination · Retains Piperine, total phenolics, microbial load, colour, volatile oil
Radio-frequency heating of inoculated black peppercorns for 2.5 min reduced Salmonella by 5.31 log CFU/g and the surrogate Enterococcus faecium by 5.26 log CFU/g across the whole tray. Colour, piperine content, total phenolics, radical-scavenging activity and most of the volatile compounds in the treated peppercorns were not significantly different from the untreated control. The cold spot of the load was at the centre of the top surface.
Conditions: 2.5 min of radio-frequency heating · Peppercorns conditioned to 12.7 per cent moisture and water activity 0.60
What this does not show: Read in the abstract only. “Most” volatile compounds leaves some that did change, and the abstract does not name them. A laboratory unit and one moisture content; the result depends on the peppercorns having been conditioned to that moisture.
Measured on the spice
Decontamination · Decreases Piperine, colour, microbial load
Ground black pepper that had been steamed came out darker than untreated pepper, and its piperine fell considerably, both on treatment and over the six months of storage that followed. Irradiated pepper from the same study lost more of its microbial load and showed minimal change in composition, colour or sensory quality. Keeping the pepper at 4 °C slowed the loss of piperine.
Conditions: in steam · Followed through 6 months of storage after treatment · Steam treatment compared with irradiation; stored at refrigerator and at room temperature
What this does not show: Read in the abstract only, which gives neither the steam conditions nor any figures: “considerable” is the authors’ word. One study on pepper that was already ground, which exposes far more surface to steam than a whole peppercorn does.
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 heats are produced by unrelated molecules of vastly different potency. Scoville Heat Units are defined on capsaicinoid content and applying them to pepper is a category error, not merely an approximation.
Hydroxy-α-sanshool
Sichuan pepper is not a pepper and its sensation is not heat. The two are unrelated botanically and chemically, and the confusion is entirely an artefact of the English word "pepper".
Questions this page answers
- what is piperine
- what does piperine do
- which spices contain piperine
- what is piperin