The Scoville scale is a measurement of pungency (spiciness or "heat") of chili peppers and other substances, recorded in Scoville heat units (SHU). It is based on the concentration of capsaicinoids, among which capsaicin is the predominant component. [3]
The scale is named after its creator, American pharmacist Wilbur Scoville, whose 1912 method is known as the Scoville organoleptic test. [3] [4] The Scoville organoleptic test is a subjective assessment derived from the capsaicinoid sensitivity by people experienced with eating hot chilis. [3]
An alternative method, high-performance liquid chromatography (HPLC), can be used to analytically quantify the capsaicinoid content as an indicator of pungency. [3] [5] [6]
In the Scoville organoleptic test, an exact weight of dried pepper is dissolved in alcohol to extract the heat components (capsaicinoids), then diluted in a solution of sugar water. [3] [7] [8] Decreasing concentrations of the extracted capsaicinoids are given to a panel of five trained tasters, until a majority (at least three) can no longer detect the heat in a dilution. [1] [3] [7] [8] The heat level is based on this dilution, rated in multiples of 100 SHU. [7]
Another source using subjective assessment stated, "Conventional methods used in determining the level of pungency or capsaicin concentration are using a panel of tasters (Scoville organoleptic test method). ... Pepper pungency is measured in Scoville heat units (SHU). This measurement is the highest dilution of a chili pepper extract at which heat can be detected by a taste panel." [5] [9] [10]
A weakness of the Scoville organoleptic test is its imprecision due to human subjectivity, depending on the taster's palate and number of mouth heat receptors, which vary widely among subjects. [1] [9] Another shortcoming is sensory fatigue; [1] the palate is quickly desensitized to capsaicinoids after tasting a few samples within a short time period. [7] Results vary widely (up to ± 50%) between laboratories. [8]
Since the 1980s, spice heat has been assessed quantitatively by high-performance liquid chromatography (HPLC), which measures the concentration of heat-producing capsaicinoids, typically with capsaicin content as the main measure. [9] [5] As stated in one review "the most reliable, rapid, and efficient method to identify and quantify capsaicinoids is HPLC; the results of which can be converted to Scoville heat units by multiplying the parts-per-million by 16." [9] [lower-alpha 1]
HPLC method gives results in American Spice Trade Association 1985 "pungency units", which are defined as one part capsaicin equivalent per million parts dried pepper mass. This "parts per million of heat" (ppmH) is found with the following calculation: [5]
Peak areas are calculated from HPLC traces of dry samples of the substance to be tested in 1 ml of acetonitrile. The standard used to calibrate the calculation is 1 gram of capsaicin. Scoville heat units are found by multiplying the ppmH value by a factor of 15. [5] [lower-alpha 1] By this definition of ppmH, spicy compounds other than the two most important capsaicinoids are ignored, despite the ability of HPLC to measure these other compounds at the same time. [5]
Since Scoville ratings are defined per unit of dry mass, comparison of ratings between products having different water content can be misleading. For example, typical fresh chili peppers have a water content around 90%, whereas Tabasco sauce has a water content of 95%. [12] For law-enforcement-grade pepper spray, values from 500,000 up to 5 million SHU have been reported, [1] [13] but the actual strength of the spray depends on the dilution. [3] This problem can be overcome by stating the water content along with the Scoville value. One way to do so is the "D-value", defined as total mass divided by dry mass. [14]
Numerical results for any specimen vary depending on its cultivation conditions and the uncertainty of the laboratory methods used to assess the capsaicinoid content. [9] Pungency values for any pepper are variable, owing to expected variation within a species, possibly by a factor of 10 or more, depending on seed lineage, climate and humidity, and soil composition supplying nutrients. The inaccuracies described in the measurement methods also contribute to the imprecision of these values. [9] [8]
Capsicum chili peppers are commonly used to add pungency in cuisines worldwide. [3] [9] The range of pepper heat reflected by a Scoville score is from 500 or less (sweet peppers) to over 2.6 million (Pepper X) (table below; Scoville scales for individual chili peppers are in the respective linked article). Some peppers such as the Guntur chilli and Rocoto are excluded from the list due to their very wide SHU range. Others such as Dragon's Breath and Chocolate 7-pot have not been officially verified. [15] [16]
Scoville heat units | Examples |
---|---|
2,693,000 | Pepper X [17] |
1,500,000–2,500,000 | Carolina Reaper [18] [19] |
750,000–1,500,000 | Trinidad Moruga Scorpion, [20] Naga Viper pepper, [21] Infinity chili, [22] Ghost pepper [23] |
350,000–750,000 | Red savina habanero [24] |
100,000–350,000 | Habanero chili, [25] Scotch bonnet pepper [25] |
50,000–100,000 | Bird's eye chili (Thai chili pepper), [26] Malagueta pepper [26] |
25,000–50,000 | Tabasco pepper, [27] Cayenne pepper [28] |
10,000–25,000 | Serrano pepper, [29] Aleppo pepper, [30] Cheongyang chili pepper [31] |
2,500–10,000 | Jalapeño pepper, [32] Guajillo chili [33] |
1,000–2,500 | Poblano pepper [34] [35] |
500–1,000 | Cubanelle, [26] Beaver Dam pepper [36] |
0–500 | Pimiento [37] |
0 | Bell pepper, Peperone crusco [38] |
The class of compounds causing pungency in plants such as chili peppers is called capsaicinoids, which display a linear correlation between concentration and Scoville scale, and may vary in content during ripening. [39] Capsaicin is the major capsaicinoid in chili peppers. [5]
The Scoville scale may be used to express the pungency of other, unrelated TRPV1 agonists, sometimes with extrapolation for much hotter compounds. One such substance is resiniferatoxin, an alkaloid present in the sap of some species of euphorbia plants (spurges). Since it is 1000 times as hot as capsaicin, it would have a Scoville scale rating of 16 billion. [40] In the table below, non-capsaicinoid compounds are italicized.
Scoville heat units | Chemical | Ref. |
---|---|---|
16,000,000,000 [lower-alpha 2] | Resiniferatoxin | [41] |
5,300,000,000 [lower-alpha 2] | Tinyatoxin | [42] |
16,000,000 | Capsaicin | [43] [44] |
15,000,000 | Dihydrocapsaicin | [43] |
9,200,000 | Nonivamide | [43] |
9,100,000 | Nordihydrocapsaicin | [43] [44] |
8,600,000 | Homocapsaicin, Homodihydrocapsaicin | [43] |
160,000 | Shogaol | [45] |
150,000 | Piperine | [46] |
60,000 | Gingerol | [45] |
Capsaicin (8-methyl-N-vanillyl-6-nonenamide) is an active component of chili peppers, which are plants belonging to the genus Capsicum. It is a chemical irritant for mammals, including humans, and produces a sensation of burning in any tissue with which it comes into contact. Capsaicin and several related amides (capsaicinoids) are produced as secondary metabolites by chili peppers, likely as deterrents against certain mammals and fungi. Pure capsaicin is a hydrophobic, colorless, highly pungent crystalline solid.
The bell pepper is the fruit of plants in the Grossum Group of the species Capsicum annuum. Cultivars of the plant produce fruits in different colors, including red, yellow, orange, green, white, chocolate, candy cane striped, and purple. Bell peppers are sometimes grouped with less pungent chili varieties as "sweet peppers". While they are botanically fruits—classified as berries—they are commonly used as a vegetable ingredient or side dish. Other varieties of the genus Capsicum are categorized as chili peppers when they are cultivated for their pungency, including some varieties of Capsicum annuum.
Chili peppers, also spelled chile or chilli, are varieties of the berry-fruit of plants from the genus Capsicum, which are members of the nightshade family Solanaceae, cultivated for their pungency. Chili peppers are widely used in many cuisines as a spice to add "heat" to dishes. Capsaicin and related compounds known as capsaicinoids are the substances that give chili peppers their intensity when ingested or applied topically. Chili peppers exhibit a range of heat and flavors. This diversity is the reason behind the availability of different types of paprika and chili powder, each offering its own taste and heat level.
Capsicum pubescens is a plant of the genus Capsicum (pepper). The species name, pubescens, refers to the hairy leaves of this pepper. The hairiness of the leaves, along with the black seeds, make Capsicum pubescens distinguishable from other Capsicum species. Capsicum pubescens has pungent yellow, orange, red, green or brown fruits.
Hot sauce is a type of condiment, seasoning, or salsa made from chili peppers and other ingredients. Many commercial varieties of mass-produced hot sauce exist.
Capsicum annuum var. glabriusculum, a chili-pepper variety of Capsicum annuum, is native to southern North America and northern South America. Common names include chiltepín, Indian pepper, grove pepper, chiltepe, and chile tepín, as well as turkey, bird’s eye, or simply bird peppers. Tepín is derived from a Nahuatl word meaning "flea". This variety is the most likely progenitor of the domesticated C. annuum var. annuum. Another similar-sized pepper, 'Pequin' is often confused with tepin, although the tepin fruit is round to oval where as the pequin's fruit is oval with a point, and the leaves, stems and plant structures are very different on each plant.
Capsicum annuum is a fruiting plant from the family Solanaceae (nightshades), within the genus Capsicum which is native to the northern regions of South America and to southwestern North America. The plant produces berries of many colors including red, green, and yellow, often with pungent taste. It also has many varieties and common names including paprika, chili pepper, jalapeño, cayenne, bell pepper, and many more with over 200 variations within the species. It is also one of the oldest cultivated crops, with domestication dating back to around 6,000 years ago in regions of Mexico. The genus Capsicum has over 30 species but Capsicum annuum is the primary species in its genus, as it has been widely cultivated for human consumption for a substantial amount of time and has spread across the world. This species has many uses in culinary applications, medicine, self defense, and can even be ornamental.
Dihydrocapsaicin is a capsaicinoid and analog and congener of capsaicin in chili peppers (Capsicum). Like capsaicin, it is an irritant. It accounts for about 22% of the total capsaicinoid mixture and has the same pungency as capsaicin. Pure dihydrocapsaicin is a lipophilic colorless odorless crystalline to waxy compound. It is soluble in dimethyl sulfoxide and 100% ethanol.
Nordihydrocapsaicin is a capsaicinoid and analog and congener of capsaicin in chili peppers (Capsicum).
Homodihydrocapsaicin is a capsaicinoid and analog and congener of capsaicin in chili peppers (Capsicum). Like capsaicin it is an irritant. Homodihydrocapsaicin accounts for about 1% of the total capsaicinoids mixture and has about half the pungency of capsaicin. Pure homodihydrocapsaicin is a lipophilic colorless odorless crystalline to waxy compound. It produces "numbing burn" in the throat and is one of the most prolonged and difficult to rinse out. On the Scoville scale it has 8,600,000 SHU.
Homocapsaicin is a capsaicinoid and analog and congener of capsaicin in chili peppers (Capsicum). Like capsaicin it is an irritant. Homocapsaicin accounts for about 1% of the total capsaicinoids mixture and has about half the pungency of capsaicin. Pure homocapsaicin is a lipophilic colorless odorless crystalline to waxy compound. On the Scoville scale it has 8,600,000 SHU. Homocapsaicin isolated from chili pepper has been found in two isomeric forms, both with a carbon-carbon double bond at the 6 position on the 10-carbon acyl chain. One isomer has an additional carbon, a methyl group, at the 8 position and the other has a methyl group at the 9 position. Homocapsaicin (6-ene-8-methyl) is the more abundant isomer. Homocapsaicin with the double bond at the 7 position has never been found in nature, though its structure is widely reported on the Internet and in the scientific literature. Details of this misidentification have been published.
The Red Savina pepper is a cultivar of the habanero chili, which has been selectively bred to produce spicier, heavier, and larger fruit, ultimately more potent than its derivative.
The Naga Morich is a chili pepper originally grown in India and Bangladesh. There is no consensus on whether this is synonymous with the Bhut Jolokia, or a different variety. It is also one of the hottest known chilli peppers and the only naturally occurring chili pepper that measures 1 million SHU on Scoville scale. Morich is the word for chilli pepper in Bengali, with similar words in Assamese:, Nepali, Hindi and the languages of Nagaland and Manipur. Naga Morich is registered under the Geographical Indications (GI) of Nagaland by Government of India.
Siling labuyo is a small chili pepper cultivar that developed in the Philippines after the Columbian Exchange. It belongs to the species Capsicum frutescens and is characterized by triangular fruits that grow pointing upwards. The fruits and leaves are used in traditional Philippine cuisine. The fruit is pungent, ranking at 80,000 to 100,000 heat units in the Scoville Scale.
A guajillo chili or guajillo chile or chile guaco or mirasol chile is a landrace variety of the species Capsicum annuum with a mirasol chile fruit type. Mirasol is used to refer to the fresh pepper, and the term guajillo is used for the dry form, which is the second-most common dried chili in Mexican cuisine. The Mexican state of Zacatecas is one of the main producers of guajillo chilies. There are two main varieties that are distinguished by their size and heat factors. The guajillo puya is the smaller and hotter of the two. In contrast, the longer and wider guajillo has a more pronounced, richer flavor and is somewhat less spicy. With a rating of 2,500 to 5,000 on the Scoville scale, its heat is considered mild to medium.
Pungency refers to the taste of food commonly referred to as spiciness, hotness or heat, found in foods such as chili peppers. Highly pungent tastes may be experienced as unpleasant. The term piquancy is sometimes applied to foods with a lower degree of pungency that are "agreeably stimulating to the palate". Examples of piquant food include mustard and curry. The primary substances responsible for pungent taste are capsaicin, piperine and allyl isothiocyanate.
The Carolina Reaper chili pepper is a cultivar of the Capsicum chinense plant. Developed by American breeder Ed Currie, the pepper is red and gnarled, with a bumpy texture and small pointed tail. It was the hottest chili pepper in the world according to Guinness World Records from 2013 to 2023 before it was surpassed by Pepper X, which was also developed by Currie.
The ghost pepper, also known as bhüt jolokia, is an interspecific hybrid chili pepper cultivated in Northeast India. It is a hybrid of Capsicum chinense and Capsicum frutescens.
Capsicum is a genus of flowering plants in the nightshade family Solanaceae, native to the Americas, cultivated worldwide for their edible fruit. Sweet or bell peppers and some chili peppers belong to the Capsicum annuum species, making it the most cultivated species from the genus.
The habanero is a hot variety of chili. Unripe habaneros are green, and they color as they mature. The most common color variants are orange and red, but the fruit may also be white, brown, yellow, green, or purple. Typically, a ripe habanero is 2–6 centimetres long. Habanero chilis are very hot, rated 100,000–350,000 on the Scoville scale. The habanero heat, flavor, and floral aroma make it a common ingredient in hot sauces and other spicy foods.
Interlab variation [for the original Scoville scale] could be as high as +/−50%. However, labs that run these procedures could generate reasonably repeatable results.
Most law enforcement sprays have a pungency of 500,000 to 2 million SHU. One brand has sprays with 5.3 million SHU.
Carolina Reaper, known to reach as many as 2.2 million S.H.U.s — more potent than some pepper sprays — and certified by Guinness World Records as the hottest chile on earth.
Any pepper type with ≥ 1 SHU could be considered spicy. However, for this study, paprika (0–300 SHU), New Mexico long green or red chile (300–500 SHU), and poblano/ancho (≈1369 SHU) types were included as mild spicy peppers (Table 1).
Reported pungencies for pepper varieties (in Scoville units) are: Habanero (H), 100,000–300,000; Thai green (T), 50,000–100,000; wax (W), 5,000–10,000; and Poblano verde (P), 1,000–1,500 (ref. 23).