The 7 Pot Barrackpore starts at the same Scoville Heat Unit (SHU) as the regular ones, but its highest level has frequently approached 1.3M SHU, which can easily set your face on fire. How the name Barrackpore came about, though, is quite intriguing.

This is the third tweet in a medium-sized thread on Twitter by @Paperclip_In whose length belies the scope of the story it narrates. The thread takes off from the pepper in question, the 7 Pot Barrackpore from Trinidad, winds its way through the famous rebellion of 1857, the fortunes of indentured labourers shipped from India to the Caribbean in the late 19th and early 20th centuries, and ends – as it began – with the town of Barrackpore. All of this in a name, the name shared by two towns 15,000 km apart.

Reading the thread was fascinating for two reasons. One, of course, was @Paperclip_In’s narration itself; the other was that what little I already knew about hot peppers and Scoville heat units is also tethered to another fervent piece of history.

Last year’s medicine Nobel Prize was awarded to two scientists for their work on the receptors in the body that were involved in our ability to perceive heat and cold. The work of one of the laureates, David Julius, was based on studying the effects of a compound called capsaicin on the body. Capsaicin is technically 8-methyl-N-vanillyl-6-nonenamide.

As I wrote at the time, “Capsaicin doesn’t actually burn or damage tissue. Its contact with [a receptor expressed by central nervous system cells] simply prompts the brain to react as if the tissue is being burnt.” This feature of the compound obviously stood out to those interested in new forms of inflicting pain on others. Former MP Lagadapati Rajagopal caused a commotion in Parliament in 2014 when he released an emulsified and pressurised capsaicin resin from a cannister, to oppose the bifurcation of Andhra Pradesh.

The SHU of any spicy pepper denotes its capsaicin content. Capsaicin itself has an SHU of 16 million – the upper limit. The SHU of 7 Pot Barrackpore is around 1.3 million. In 2007, the chilli with the world’s highest SHU was ‘Naga chilli’ from Northeast India. In 2010, Associated Press reported that DRDO scientists were developing grenades packed with capsaicin extracted from the Naga chilli.

In 2016, a committee appointed by the Indian government was still considering these ‘chilli grenades’ as substitutes for pellet guns, but eventually decided to load the things with nonivamide. @Paperclip_In is right to describe the 7 Pot Barrackpore, with an SHU of 1.3 million, as being able to “set your face on fire”. Nonivamide has an SHU of more than 9 million.