With the approach of International Hot and Spicy Food Day, which this year is to be celebrated on 16 January, it seems a good time to write again about the pungency of chilli peppers, which depends on the capsaicin present in the fruit.

Nowadays a pepper’s capsaicin content can be assessed using analytical techniques such as high-performance liquid chromatography. In future it may be measured more quickly and cheaply using carbon nanotubes. But for most of the 20th century the piquancy of chilli peppers was measured by a technique devised in 1912 by a US pharmacist.

Wilbur Scoville was born on 22 January 1865. He created his “Scoville organoleptic test” in 1912 while working for the Parke-Davis pharmaceutical company. He tried many different chemical methods for measuring chilli pungency but found the readings imprecise and inconsistent. He then decided that subjective tests would be more successful.

His chosen method involved adding a standardised extract of capsaicin oil from dried pepper to a sugar solution until the “heat” was just detectable by a panel of tasters. The degree of dilution gave the chilli’s measure on the Scoville scale. A weakness of his test is a lack of precision because it depends on human subjectivity. Another problem is that tasters can only reliably taste one sample per session. Despite these snags, his creation was the only test method available for decades.

Scoville was also a successful author, his best known work being ‘The art of compounding’, which became a standard pharmacy reference book. First published in 1895, it was updated regularly for more than 50 years. A facsimile reprint of an early edition was published in 2010.

Scoville’s work was recognised by two awards from the American Pharmaceutical Association. In 1922, he won the association’s Ebert prize (given for “the best report of original investigation of a medicinal substance”) and in 1929 he received the association’s most prestigious prize, the Remington Honor Medal.

Scoville died in 1942, aged 77.