Heat Chemistry and Wilbur Scoville

Found at:
http://easyweb.easynet.co.uk/~gcaselton/chile/scoville.html

Chemistry and Wilbur Scoville

It was in 1912 whilst working forthe Parke Davis pharmaceutical company that one of their chemists, Wilbur Scoville, developed a method to measure the heat level of a chile pepper. 

This test is named after him, it's called the Scoville Organoleptic Test, and it's a dilution-taste procedure.

In the original test, Scoville blended pure ground chiles with a sugar-water solution and a panel of testers then sipped the concoctions, in increasingly diluted concentrations, until they reached the point at which the liquid no longer burned the mouth.

A number was then assigned to each chile based on how much it needed to be diluted before you could taste no heat.

The pungency of chile peppers is measured in multiples of 100 units, from the bell pepper at zero Scoville units to the incendiary Habanero at 300,000 Scoville units!

One part of chile "heat" per 1,000,000 drops of water rates as only 1.5 Scoville Units. The substance that makes a chile so hot (and therefore so enjoyable to Chile-Heads !), is Capsaicin. Pure Capsaicin rates over 15,000,000 Scoville Units !

The "Red Savina" Habanero has been tested at over 577,000 Scoville units!

This is so much hotter than the normal Habanero chile pepper, that the "Guinness Book of Records" has accepted it as "the hottest chile pepper" in the world. Even now, breeders are attempting to beat this. The new Francisca Habanero is said to be hotter still!

Stop Press

The new title holder, according to experts at the Defense Research Laboratory in the army garrison town of Tezpur in the north-eastern state of Assam, is the local Naga Jolokia (capsicum frutescens).

It was nearly 50 per cent more pungent than the Red Savina Habanero from Mexico.

"Laboratory tests have confirmed that Naga Jolokia, a specialty from the north-east, is now the world's hottest chilli," the laboratory's deputy director S.C. Das said by telephone from Tezpur.

The Naga Jolokia is grown mostly in the hilly terrain of north-east India and is a staple in every meal among local tribals.

http://www.poole-associates.com/chilli.htm

PLEASE NOTE ... that there has been NO additional information about this variety. Chile-Heads around
the world suspect that it is only media hype and not real factual reporting......we wait and see!

Read further about the Naga Jolokia at:

The Daily Star Internet Edition @
http://www.dailystarnews.com/200009/06/n0090613.htm

SAfm Headlines @ 
http://www.safm.co.za/headlines/sep2000/head2_0609.html

India Abroad News Service @
http://news.indiainfo.com/2000/09/04/04chili.html

The validity and accuracy of the Scoville Organoleptic test have been widely criticized. The American Spice Trade Association and the International Organization for Standardization have adopted a modified version. The 
American Society for Testing and Materials is considering other organoleptic  tests (the Gillett method) and a number of other chemical tests to assay for capsaicinoids involved in pungency. Even so, the values obtained by these  various tests are often related back to Scoville Units. Nowadays the  High-Performance Liquid Chromatography (HPLC) test is used. In this  procedure, chile pods are dried, then ground. Next, the chemicals responsible for the pungency are extracted,  and the extract is injected into the HPLC for analysis. This method is more  costly than the previous, but it allows an objective heat analysis. Not only  does this method measure the total heat present, but it also allows the  amounts of the individual capsaicinoids to be determined. In addition, many  samples may be analyzed within a short period.

~~~~~~~~~ Capsaicin

As a result of all these tests, various varieties of chile peppers can be ranked according to their heat or "pungency" level:
  

Here, causing some of the "pain", is the chemical composition of the better known of the Capsaicinoids  (courtesy of John Henninge M.Sc.)

Capsaicin

Dihydrocapsaicin

Nordihydrocapsaicin

Homocapsaicin

Capsaicin, also known as N-Vanillyl-8-methyl-6-(E)-noneamide, is the most  pungent of the group of compounds called Capsaicinoids that can be isolated  from chile peppers. It is sparingly soluble in water, but very soluble in  fats, oils and alcohol. The minor Capsaicinoids include Nordihydrocapsaicin  [Dihydrocapsaicin with a (CH2)5 instead of (CH2)6], Homocapsaicin [Capsaicin  with a (CH2)5 instead of (CH2)4, and Homodihydrocapsaicin [Dihydrocapsaicin  with a (CH2)7 instead of (CH2)6].

Capsaicin and Dihydrocapsaicin together make up 80-90% of the Capsaicinoids found in peppers. In the Capsicum annum species, the total Capsaicinoid content ranges from 0.1 to 1.0%, and the Capsaicin to Dihydrocapsaicin ratio is about 1:1.

In Capsicum frutescens the total content ranges from 0.4-1.0% with the ratio around 2:1.

Given all these various molecules, tests have shown that the Capsaicinoids can be ranked according to their heat or "pungency" level:

At 8,600,000         Scoville Units is Homocapsaicin.

At 8,600,000        Scoville Units is Homodihydrocapsaicin.

At 9,100,000       Scoville Units is Nordihydrocapsaicin.

At 16,000,000     Scoville Units is Dihydrocapsaicin.

At 16,000,000     Scoville Units is Pure Capsaicin.

In order to douse the heat when eating chile peppers, try drinking milk or eating ice cream or yoghourt. These dairy products are especially effective at breaking down the Capsaicin oils, which are not soluble in water.

For more detailed chemistry of Capsaicin and other vanilloids, the Frostburg State University has a very good web page with some useful links to other sites.

Dave DeWitt has written an interesting article titled 'The Nature of Capsaicin'.

The Brooklyn Botanic Garden has an interesting article by Paul Bosland on 'What makes Chile Peppers hot?'

"The least irritating capsaicinoid is Nordihydrocapsaicin, according to researchers at the University of Georgia. They found that the burning is located in the front of the mouth and palate, causing a "mellow warming effect." The pungency sensation develops immediately after swallowing and recedes rapidly.

In comparison, capsaicin and Dihydrocapsaicin were found to be more irritating, and were described as having a "typical" pungency sensation. Both compounds produce pungency in the middle of the mouth, the middle of the palate, the throat, and the back of the tongue.

In contrast, Homodihydrocapsaicin is very irritating, harsh, and very sharp. The pungency does not develop immediately but it affects the throat, back of the tongue, and the palate for a prolonged period."

Other compounds

A recent paper in Journal. Sci. Food Agric., 1995, 67, 189-196 by S.M. van  Ruth, J.P. Roozen and J.L. Cozijnsen, and available at The Department of  Chemistry, University of the West Indies, describes flavour components in  Bell peppers. Out of 47 compounds identified, 12 could be detected by  assessors at a sniffing port on a Gas Chromatograph:

3 (2220) 2-Methylpropanal

9 2-Methylbutanal

10 3-Methylbutanal

13 (2370) 2,3-Butanedione

15 (3382) 1-Penten-3-one

19 (2557) Hexanal

25 (2540) Heptanal

29 beta-Ocimene

35 trans-3-Hepten-2-one

39 Dimethyltrisulfide

45 (3132) 2-isobutyl-3-methoxypyrazine

47 (3639) beta-Cyclocitral

other compounds found in reasonable quantities were:

14 (3098) Pentanal

21 1-Methyl-1H-pyrrole

23 (3584) 1-Penten-3-ol

26 (2633) (R)-(+)-Limonene

36 cis-2-Heptenal

40 (2782) Nonanal

42 (2805) 1-Octen-3-ol

44 (2362) Decanal

The compound described as the character imparting compound in Bell peppers is 2-isobutyl-3-methoxypyrazine. This very powerful odorant has a threshold in water of 1 part in 10^12.

Beer and water will only spread the flames !!

The following information is a guide to the process for the crude  purification of Capsaicin that I found on the net.

Follow it at your own risk !

Ingredients:

15 Habanero peppers
1 quart 200 proof Ethanol

Method:

In a blender, puree the Habanero's in as much Ethanol as possible. Let the mixture sit overnight at room temperature.

Pour the resultant sludge through paper towels and place the liquid in a glass container. Begin to heat the liquid very slowly using either an electric heating device (naked flames would be dangerous), or use a vapor trap to remove the alcohol fumes safely.

Continue until 90% of the liquid has evaporated. Remove from the heat and let cool. Look for a brick-red oil floating on the surface of the ethanol. If none is present, continue to evaporate the ethanol away periodically cooling the mixture to look for the red oil on the surface. Once the red oil appears, pour the red oil and the remaining ethanol into a long thin glass cylinder, use an eye dropper to suck off the oil and place it in a clean container. The red oil is fairly pure Capsaicin, probably 40% Capsaicin / 60% Capsaicinoids.

Please bear in mind that Capsaicin is an extreme irritant and is hazardous to health as both a chemical burn agent and as a poison when in its purer concentrated forms. Only a fool or a chemist would want to undertake the above procedure

See Sigma-Aldrich publications for further information

Suggested reading and references

Govindarajan, VS and Sathyanarayana, MN; Capsicum - Production, Technology, Chemistry and Quality. Part V. Impact on Physiology, Nutrition and Metabolism; Structure, Pungency, Pain and Desensitisation Sequences, Crit. Rev. Food Sci. Nutr. 29, 435. 1991

"Peppers: History and Exploitation of a Serendipitous New Crop Discovery" by W. Hardy Eshbaugh, in New Crops, edited by Janick & Simon, 1993.

New Mexico State University, Measuring Chile Pungency by Margaret Collins, Research Specialist and Paul W. Bosland, Prof. of Vegetable Breeding and Genetics.

Many thanks to the Sunday Times for the review in the following article:

June 3 2001 DOORS

Feeling hot? Robbie Hudson is sweltering too

Testing is now carried out using liquid chromatography, as the helpful

http//:www.easyweb.easynet.co.uk/~gcaselton/chile/scoville.html explains. It also informs you that the hottest pepper is the red savina (577,000), and reveals how to refine pure capsaicin (a terrifying 15m Scovilles). It adds that only a fool would do this. Drinking aftersun lotion will not soothe any resultant burning.

http://easyweb.easynet.co.uk/~gcaselton/chile/scoville.html