Black pepper: the spice whose scent comes from rotundone

Where does black pepper come from?

Black pepper comes from Piper nigrum, a flowering vine in the Piperaceae family native to South Asia, possibly to India's Malabar Coast, where wild pepper still grows in the Western Ghats. Wikipedia's black pepper article explains the colours: black pepper is made from unripe drupes, briefly cooked then dried; white pepper is only the seed of the ripe fruit; green pepper is unripe fruit preserved to keep its colour. In 2023 Vietnam produced 30% of the world's pepper.

What does black pepper smell like?

Black pepper smells peppery, with citrusy, woody and floral touches. Those touches come from terpenes in the outer layer of the fruit, including germacrene, limonene, pinene and beta-caryophyllene, which is why white pepper, stripped of that layer, loses most of them. Ground pepper loses its aroma quickly through evaporation, something you can test by comparing a pepper mill with a jar of ready-ground pepper.

Which molecule gives black pepper its smell?

Rotundone gives black pepper its peppery aroma, and you can detect it at around 0.4 ng/L. Wikipedia's rotundone article describes it as a sesquiterpene first found in the tubers of nutgrass (Cyperus rotundus) and also present in the essential oils of marjoram, oregano, rosemary, basil, thyme and geranium, as well as in some Syrah wines. Piperine, by contrast, brings the heat but not the smell.

What should you know about black pepper?

Black pepper yields an essential oil by extraction from crushed dried peppercorns. Three of its terpenes, limonene, pinene and beta-caryophyllene, are among the fragrance allergens that Regulation (EU) 2023/1545 requires on cosmetic labels above a threshold. Black pepper sits in the woody family; compare it with pink pepper, which is not a pepper at all, and with geranium, which also contains rotundone.