Sansho vs Black pepper
The short answer
Two spices called pepper and neither of them related to the other or to Piper nigrum in the case of the first. Black pepper is Piper nigrum and its pungency comes from piperine, a chemical irritation. Sanshō is a Zanthoxylum, a citrus relative, and it does not burn at all: hydroxy-alpha-sanshool produces a tingling numbness by acting on the nerves that sense touch. They are not different intensities of the same sensation but different sensations.
Side by side
| Sansho | Black pepper | |
|---|---|---|
| Botanical identity | Zanthoxylum piperitum (L.) DC. | Piper nigrum L. |
| Part used | fruit, leaf | fruit, berry |
| Origin | Japan and the Korean peninsula, where the species is native. | The Malabar coast of southwestern India. |
| Flavour notes | citric, green, tingling, resinous, numbing | pungent, woody, citrus, resinous, warming |
| Heat | Scoville does not apply | Scoville does not apply |
| Flavour | Bright and citric, with a tingling numbness that arrives a second or two later and is milder and shorter-lived than Sichuan pepper’s. There is no heat: the sensation is a vibration on the lips and tongue rather than a burn, and it is produced by acting on the nerves for touch rather than for temperature. | Pungent and warming with a woody, faintly citric aroma behind the bite. The pungency builds and lingers rather than striking immediately as chilli heat does. |
| Aroma | Sharply citric and green — grapefruit peel and lime leaf, with a resinous edge. It is much more overtly citrus than Sichuan pepper and much less floral. | Woody, resinous and citrus-fresh, with a distinct piney lift that is lost quickly once ground. |
Which should you buy?
Sansho
Whole husks if you can get them, and a very small jar of the powder if you cannot. This is one of the few entries in the catalogue where the whole-versus-ground argument is not about nuance but about whether the spice works at all: hydroxy-alpha-sanshool degrades fast once the husk is broken, and a large jar of ground sansho is a purchase that will be inert before it is finished. Buy little and often, and test it on your tongue rather than by smell.
Black pepper
This is the least ambiguous whole-versus-ground case in the entire spice cupboard. Pepper's pungency is non-volatile and its aroma is highly volatile, so pre-ground pepper reliably delivers the heat and reliably loses the fragrance. Buy whole and grind at the point of use; nothing else about pepper matters as much.
Full detail on sansho and black pepper, including evidence grades and sources for every claim above.