Chile heat levels are the results of two factors, the plant’s genetics and the environment in
which it grows. Although plant breeders can produce a chile
with a certain amount of relative heat, genetic control is not yet
fully understood. For example, ‘NuMex Joe E. Parker’ was
selected to produce “medium” heat pods. However, the
environment, water amounts and temperature levels, in which
this particular variety is grown will have great effects on the
heat levels.

Methods to Determine Heat

The most common way to test chile heat is to taste the pod.
This method, although quick and cost effective, may leave the
tester in some pain. There are two other ways of testing heat;
(1)The Scoville Organoleptic test and (2)High Performance

Liquid Chromatography.

The Scoville test is a refined, systematic approach. It was the
first laboratory approach used to measure heat in chiles. In this
method human subjects taste a chile sample and record the heat
level. The samples are diluted in the laboratory until heat can
no longer be detected by the tasters. This dilution is called the Scoville Heat Unit. This
procedure can be appropriate in many circumstances, as it is more accurate than a taste
test. This test is also less expensive than more advanced laboratory techniques, but this
method has limitations. Measuring heat with this technique is still subjective and depends
on the taster’s palate and sensitivity to the chemicals that are responsible for heat. In
addition, there are serious limits on how many samples a taster can handle within a
reasonable time.

High-Performance Liquid Chromatography

The most accurate method for measuring heat in chiles is a High Performance Liquid
Chromatography (HPLC). In this procedure, chile pods are dried, then ground. Next, the
chemicals responsible for the heat are extracted, and the extract is injected into the HPLC
device for analysis. This method is more costly than the Scoville but much more accurate.
This method measures the total heat present as well as the individual capsaicinoids
present.

SCOVILLE HEAT UNITS SCALE

The following is a list of chiles, put into a scale to show the relative heat levels and their
Scoville Heat Units.*

Name Species Scoville Units
Orange Habanero chinense 210,000
Red Habanero chinense 150,000
Tabasco frutescens 120,000
Chiltepin annuum 75,000
Thai Hot annuum 60,000
Serrano annuum 25,000
Long Slim Cayenne annuum 23,000
Mitla annuum 22,000
Santa Fe Grande annuum 21,000
Aji Escabeche baccatum 17,000
Long Thick Cayenne annuum 8,500
Jalapeno M annuum 5,500
NuMex Primavera annuum 5,000
NuMex Sandia annuum 5,000
NuMex Joe E. Parker annuum 4,500
Pasilla annuum 4,000
Mulato annuum 1,000
Bell annuum 0

*We would like to stress that this research was the result of combined averages taken
from two different locations. This causes variation in heat levels, general heat levels are
consistent for that particular variety or species. For examples, Red Habaneros are
generally hotter than Orange and Jalapeño’s can range anywhere from 4,000 Scoville heat
units to 50,000 Scoville heat units. ‘Mitla’ is considered a medium jalapeño, while
‘NuMex Primavera’ is considered to be mild.

This is a publication of the Chile Pepper Institute, New Mexico State University.