The Scoville scale is the world recognized scale for measuring the heat in chillies and other peppers. The scale was created in the early 1900’s by pharmacist Wilbur L. Scoville.
Scoville’s method was simple, yet very effective. He soaked each different variety of pepper separately in alcohol overnight. Because capsaicin is soluble in alcohol, the soaking extracted the pungent chemicals from the pod. Then he took a precise measure of the extract and to it added sweetened water in incremental portions until the heat was barely detectable on his tongue.
Scoville Heat Units (SHUs)
An SHU is the actual number assigned to the heat of a pepper. A chili with a rating of 0 Scoville Heat Units (SHUs), means that there is no heat detectable.
As an example, in the case of Japanese chilies, it took sweetened water in volumes between 20,000 to 30,000 times the pepper extract before the heat was barely discernible. He thus rated the Japanese chilies 20,000 to 30,000 Scoville Heat Units. Jalapenos were rated 3,000 to 5,000, and Tabasco 30,000 to 50,000. The hottest chillies Scoville tested was a naga jolokia which is primarily found native to Bangladesh which he measured at 850,000-1,000,000 Scoville units.
Scoville’s name has since become closely associated with the measure of pungency (heat), but the oral test is now being slowly replaced by a modern machine. Using High Pressure Liquid Chromatography, analytical chemistry has now replaced the testing that used to be performed by the sensitive human tongue and unlike Scovilles method, numerous tests can be conducted each day.
When choosing to Grow Chilles, look at the Scoville scale and choose a chili that will suit your tastes. My favorite is birds eye chili but they are quite hot coming in at about 50,000-100,000 Scoville Units.