Do you know the Scoville Scale [Scoville Heat Units (SHU)]?

The Scoville scale is a measurement of the pungency of chili peppers and other spicy foods, as recorded in Scoville Heat Units (SHU) based on the concentration of capsaicinoids, among which capsaicin is the predominant component. 

Pungency means spiciness or "heat" of chili peppers and other spicy foods, Capsaicinoids are class of compounds causing pungency in plants like chili peppers. Examples of Capsaicinoids includes; Resiniferatoxin, Tinyatoxin, Capsaicin, Dihydrocapsaicin, Nonivamide, Nordihydrocapsaicin, Homocapsaicin, Homodihydrocapsaicin, Shogaol, Piperine, Gingerol and Capsiate. Later on this article you'll see these compounds with their scoville heat units (SHU).

The scale is actually a measure of the concentration of the chemical compound capsaicin which is the active component that produces the heat sensation for humans. The name capsaicin comes from the scientific classification of the pepper plant, a type of fruit, that belongs to the genus Capsicum.

Capsaicin occurs naturally in chilli peppers together with a number of very similar compounds referred to generically as capsaicinoids, it is the precise ration of these capsaicinoids which causes the differences in taste reaction to different pepper species. To know more about the origin of Svoville Scale (Scoville heat units) CLICK HERE.

Scoville heat units (SHU) [Scoville Scale] is determined by two methods, Scoville organoleptic test and Pungency units, the following are descriptions about these two methods.

1. Scoville organoleptic test       

Scoville organoleptic test involve an exact weight of dried pepper which dissolved in alcohol to extract the heat components (capsaicinoids), then diluted in a solution of sugar water. 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. The heat level is based on this dilution, rated in multiples of 100 SHU.

Conventional methods used in determining the level of pungency or capsaicin concentration are using a panel of tasters (Scoville Organoleptic test method). This measurement involve the highest dilution of a chili pepper extract at which heat can be detected by a taste panel.

Scoville organoleptic test has many weakness, is not accuracy compared to 'Pungency units method' because its imprecision is due to human subjectivity, depending on the taster's palate and number of mouth heat receptors, which vary widely among people. Also because of sensory fatigue; the palate is quickly desensitized to capsaicinoids after tasting a few samples within a short time period. Results vary widely (up to ± 50%) between laboratories.

2. Pungency units       

This method is more accuracy than the first one, involve the use high-performance liquid chromatography (HPLC) for analytical quantification of the capsaicinoid content as an indicator of pungency.

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.

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. HPLC results permit the measurement of a substance’s capsaicin capacity to produce perceived heat ("pungency"). This method gives results in American Spice Trade Association "pungency units", which are defined as one part capsaicin per million parts dried pepper mass.

For parts per million (ppm) measurements, SHU units are calculated from "parts per million of heat" (ppmH), Scoville heat units are found by multiplying the ppmH value by a factor of 15 or 16. 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.

The following are level of pungency in terms of Scoville units;

Examples of Chili pepper with their Scoville Heat Units (SHU)

Capsicum chili peppers are commonly used to add pungency in cuisines worldwide. The range of pepper heat reflected by a Scoville score is from 100 or less (sweet peppers) to over 3 million (Pepper X)

Examples of Capsaicinoids (Capsaicin pharmacophore) with their Scoville Heat Units (SHU).

Capsaicin pharmacophore (Capsaicinoids), are class of compounds causing pungency in plants like chili peppers, which display a linear correlation between concentration and Scoville scale, and may vary in content during ripening. Capsaicin is the major capsaicinoid in chili peppers. The following are examples of these compounds with their SHU.

CONCLUSION

Numerical results for any specimen vary depending on its cultivation conditions and the uncertainty of the laboratory methods used to assess the capsaicinoid content. 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.

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Posted by: Lusubilo A. Mwaijengo