The Scoville scale of spiciness

The best way to realize that one pepper, chili or chilli is more hot than another is to try it (go to the bathroom, dry tears, drink half of the water reserves in Spain, ask for the meaning of life, etc.). Unlike the latter, with the Scoville scale , the amount of spiciness of a product can be technically analyzed.



Basic scale of the most famous chili peppers. Errata: Pure capsaicin has 16,000,000 SHUs.


Wilbur Scoville was an American-born chemist. In 1912, he carried out tests at the Parke-Davis pharmaceutical company (a subsidiary of the pharmaceutical company Pfizer) to determine the amount of spiciness in each chilli or chili. That was the milestone in his history as a chemist who gives his name to this famous spicy scale but was also related to perfumes and wrote a book in 1895 called The Art of Compounds that was used as


If we look at the scientific name of any pepper, whether or not it is hot, all, absolutely all chilies, peppers, of any color and shape are Capsicum annuum. Habanero chili, jalapeño, serrano, chili, cayenne, bell pepper, green frying, tree chili, Carolina Reaper, Riojan alegrías, Basque piparras, padrón peppers, chillies … and a thousand more. They are all the same thing. They differ in variety, so there are many varieties as you can see! There may be some controversy with old nomenclatures of some varieties of chili peppers. There were four species of Capsicum among which one of the most famous was C. frutescens. In the end, by international consensus and due to the taxonomic characteristics of all these species, they have agglutinated into varietals of the same Capsicum annuum species .

Whether or not a pepper is actually hot is due to this organic molecule whose name according to the IUPAC nomenclature is; hold on… 8-methyl-N-vanillyl-6-nonenamide. There is nothing. And what is the spicy effect? Capsaicin is actually an irritating compound to humans. In very high quantities it is toxic but it is very difficult, if not impossible, to become intoxicated with a cultivated chili. Another story is if we extract the pure capsaicin by laboratory methods and ingest enough of it. But it is difficult, or so far it has not been achieved, that a chili has such a concentration of capsaicin as to be fatally intoxicated. Yes, it can cause death for other reasons but not by excessive direct ingestion that causes multi-organ failure, for example. The fatal dose in mice has been established to be 100 mg per kilogram of body weight. But let’s leave it there.

Chile Trinidad Moruga Scorpion. One of the hottest in the world. Source: Wikimedia commons

Although it is true that there are international competitions of hot chili varieties with an absolute barbarity of SHUs, today, the Pepper X variety created in 2017 by hybridizing certain varieties has been crowned as the most spicy variety, exceeding 3,000,000 units Scoville scale and far outperforming the Self Defense Pepper Sprays.

Yes, as you are reading, the personal defense sprays that are sold are nothing more than a pure capsaicin solution with an approximate concentration of 2,000,000 SHUs. Enough to leave the mucous membranes of your face (eyes, mouth, nose) a little destroyed and stunned for several minutes. However, the pepper sprays of the security forces reach 5,000,000 SHUs, already being a somewhat more dangerous weapon, being used only in extreme cases. If you want to know more about pepper sprays for personal defense, our friends at tell us about it.


Wilbur Scoville’s organoleptic examination led him to fame and even to achieve recognition in the scientific community despite being a really simple method to quantify. Although somewhat tedious for the “guinea pig” who has to undergo such an experience. Because yes, in Mr. Scoville’s time there were no such precise methods as they are today. The exam consists of the following. The chili extract solution is diluted with sugar water. Add more sugar water until testing the solution does not leave an itchy “residue”.

There is in fact a unit of measurement associated with this method that today is still the street method to establish how spicy a chili is. They are the SHU or Scoville Heat Units.

If for example the pepper has a value between 100 and 500 degrees on the Scoville scale, it  means that the pepper extract has been diluted 100 times until the capsaicin (the chemical compound that produces itching) is undetectable.

Today, the Scoville scale is not used because it is an organoleptic measure. Due to this there is a great imprecision when evaluating the spiciness of each type of chilli. A harvested habanero pepper can bite much more than another harvested from the same plant and on the same day.

Not only that, it may be that the same examiner has greater resistance to itching than another person, so the results will be different. In the first case the result is being reduced and in the second case it is exaggerated. Choosing the right person is practically impossible.

For these two main reasons, the traditional method Scoville devised has a very high bias and the SHU forks in the tables are so imprecise and have so much variability in the units displayed. But, at the end of the day, if you have tried certain chili peppers and know their approximate units, you can acquire an order of magnitude that allows you to assess whether such a hot sauce or such a chili is going to be bearable for you or not.

When more precise data than the Scoville scale are needed, chromatographic methods are used.


The spice caused by this famous element has an associated phrase that demonstrates its properties. “It’s good for everything except the stomach.” It is indeed a food preservative, it is a vasodilator and, in its fair measure, it has many cardiovascular benefits. In this article about the habanero pepper we talk about it. But without a doubt it is a pump for our digestive system and can cause very severe ulcers if it is abused. There is another widely used phrase that I learned in Mexico and it is “It stings when it enters, it stings when it comes out.” Which means that our acids are not capable of degrading so much spicy if the ingested dose exceeds tolerant limits

In addition to the cardiovascular benefits, there is a lot of medicine behind capsaicin because there are cases where it has been used as a topical pain reliever in patches for ailments such as peripheral neuropathy as you can see here. There are studies in this regard with interesting results in which these patches were used and compared with blanks (with very little or no concentration) to eliminate the bias of the placebo effect.


To measure the spiciness scale, human collaboration is needed, and that is a mistake, since we are not all the same and each one will have their own spiciness scale (some people are more tolerant of chili peppers than others).

For this reason, since 1980 there is a better and more modern system to measure the spicy scale. This is a high performance liquid chromatography (HPLC) analysis.


Below we show you the table of the tables. A table updated to January 2020 with the hottest chili peppers in the world even those that do not sting at all, taking as a reference pure capsaicin and pepper sprays. We have taken this table from Chasing chili , an Australian page referring to sauces and hot chili peppers with a small update on our part since they were missing the famous Pepper X and Dragon’s Breath that are currently the hottest although still without Guiness certification.

Leave a Reply

Your email address will not be published. Required fields are marked *