Time to replace the scoville scale ?
Sorry, Scoville. Peppers deserve
better than an archaic heat scale.
Perspective by Tamar Haspel
August 31, 2022 at 8:00 a.m. EDT
What was state of the art in 1912 has mostly fallen by the
wayside. Cars have replaced horses. Washing machines have
replaced washboards. Air travel, refrigeration and container
shipping have transformed the way we live — and that’s
before we even get to the internet.
So why, oh why, on God’s green Earth are we still measuring
chile pepper heat on the Scoville scale?
Of all the units that measure all the things, Scoville heat
units have got to be the most antediluvian. This is in no way
a diss of Wilbur Scoville, the pharmacist who came up with
this way of measuring pepper pungency back in, yes, 1912.
And in 1912, it was genius.
Here’s how it works: Take a pepper, dry it, and dissolve it in
alcohol. Then, start diluting it with sugar water. Keep
diluting it until three of a panel of five humans — yes,
humans — can no longer taste the heat. If you have to dilute
one unit of capsaicin-infused alcohol with 10,000 units of
sugar water for the pepper’s flavor to be undetectable, that
pepper rates 10,000 on the Scoville scale.
[A guide to dried chile peppers — your secret flavor weapon
in the kitchen]
It was a great system, because humans turn out to be very
good at detecting capsaicin.
But they’re not nearly as good as high-performance liquid
The heat in peppers comes from a group of chemical
compounds called capsaicinoids. The most common is
capsaicin, so we generally use that as shorthand for the heatproducing element, but there are lots of others.
And here’s the thing about capsaicinoids: We can measure
them. Without diluting them in gallons of sugar water.
Without assembling a panel of humans who have different
perceptions of heat and palates that get fatigued pretty
easily. Detecting capsaicin is absolutely, positively a job for a
“Humans differ. We vary in our taste buds and receptors,”
Paul Bosland told me, “but with a machine, we can measure
very accurately.” Bosland, now retired, studied chiles at New
Mexico State University, and his name is so closely tied to
capsaicin that, when the school raised $1 million to endow a
professorship devoted to pepper research, officials named it
after him. (The gifts official at the school, when explaining
that the interest on the money will pay the professor’s salary,
said, “That is to ensure that we will have chile research
The machine in question is that high-performance liquid
chromatograph (HPLC), which can separate the
capsaicinoids from the other components in the pepper and
tell you just how many there are in parts per million (PPM).
No taste buds required.
This is not a secret in the food industry, where machines are
widely used and panels of tasters are mostly a thing of the
past. Although an HPLC will set you back some $50,000 to
$70,000, once you have it, the testing is only about $100 a
sample, according to Bosland. Try recruiting a panel of five
humans for that price!
Pure capsaicin, in parts per million, is 1 million PPM. One
PPM translates to 16 Scoville units, so that scale tops out at
16 million. The Carolina Reaper, one of the very hottest
peppers going, comes in at 2.2 million Scoville, but there’s an
entire subculture devoted to growing — and eating —
superhot peppers, so an even hotter variety could come along
any day now.
For the rest of us, the peppers we’re likely to encounter run
the gamut. Jalapeños generally come in at 4,000-8,000.
Hungarian hot wax peppers are in the 5,000-10,000 range.
Serranos are 10,000-25,000, and habaneros, the hottest
peppers most of us are likely to cook with, start around
100,000 and can top 300,000.
And those ranges are maddening. You can grow the same
kind of pepper in the same field and get different heat levels
depending on environment, weather and ripeness. If it’s a
different cultivar, and you’re growing it in a different place,
it’s capsaicin content chaos! When you’re trying to
manufacture a food that’s supposed to taste the same every
time, that’s inconvenient. Manufacturers are used to this,
Bosland told me, and will use a combination of peppers to
get the heat level they want.
The capsaicin content doesn’t tell you everything, of course.
Peppers also have what Bosland calls a heat profile. “When
you take a bite, how fast does the heat come on? Is there a
delay? How long does that linger? Where do you sense it —
at the tip of your tongue? At the back of your throat? And is
it a sharp or flat heat? Sharp is like pins sticking you, and flat
is like a paint brush on your tongue.”
And then there’s flavor. With a very hot pepper, it’s hard to
taste past the heat, but peppers have fruity and earthy and
smoky flavors, too. When Old El Paso wanted jalapeño’s
flavor, but not its capsaicin, to blend into its products,
Bosland was able to grow a heatless jalapeño — and it won
him the 1999 Ig Nobel Prize in biology, he told me with a
laugh. (Ig Nobel Prizes, parodies of the Nobel Prizes, honor
achievements that make people laugh, think, roll their eyes
or scratch their heads.)
Now that we’ve covered the basics of peppers, let’s go back to
the original question: When we can measure parts per
million, why are we still using Scoville heat units? For
starters, the food chain is actually measuring capsaicin in
PPM, so what’s the point of converting it to a horse-andbuggy-era scale? Then there’s the fact that, by multiplying
PPM by 16 to get Scoville units, you make the ratings even
more counterintuitive than PPM; 10,000 sounds like a lot,
but it’s actually just a little. There’s got to be a better way.
Allow me to propose an alternative. A simple 1-to-10 heat
scale, based on the capsaicin content of the chile peppers
most of us encounter. Let’s use habaneros to anchor the top
end of the scale (and superhot peppers can be over 10).
Poblanos are a 1. Jalapeños are a 2, and so on, in a perfectly
understandable, simple scale based on a number we can
I thought this was a genius, original idea until I went to the
Scoville scale website and saw that it breaks peppers down
exactly this way.
I believe what’s preventing this simple, 1-to-10 scale from
catching on is the lack of a good name. Scoville was on to
something when he decided to name his scale after himself,
so I’m going to take a page from his book. Since I’m not
getting any younger, and opportunities for immortality are
thin on the ground, I think we should name this scale after
From this day forward, pepper heat will be measured in
Haspels. A habanero is a 10-Haspel pepper. Old El Paso will
make sure its salsa rolls in at 1.8 Haspels. I will be on the
signs in the pepper sections of all the grocery stores. This is
particularly appropriate since Haspels measure a substance
that can, in quantity, be pretty irritating.
You’re with me. I know you are.