A bitterant (or bittering agent) is a

chemical A chemical substance is a unique form of matter with constant chemical composition and characteristic properties. Chemical substances may take the form of a single element or chemical compounds. If two or more chemical substances can be combin ...

that is added to a product to make it smell or

taste The gustatory system or sense of taste is the sensory system that is partially responsible for the perception of taste. Taste is the perception stimulated when a substance in the mouth biochemistry, reacts chemically with taste receptor cells l ...

bitter. Bitterants are commonly used as aversive agents to discourage the inhalation or ingestion of toxic substances.

Examples of use

*The addition of a bitterant to

ethanol Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an Alcohol (chemistry), alcohol, with its formula also written as , or EtOH, where Et is the ps ...

denatures the product. *Bitterants are used in

antifreeze An antifreeze is an additive which lowers the freezing point of a water-based liquid. An antifreeze mixture is used to achieve freezing-point depression for cold environments. Common antifreezes also increase the boiling point of the liquid, allow ...

to prevent pet and child poisonings. It is required by law in some places (France, Oregon, etc.). * Gas dusters often use a bitterant to discourage inhalant abuse, although this can cause problems for legitimate users. The bitterant not only leaves a bitter flavor in the air, but also leaves a bitter residue on objects, like screens and keyboards, that may transfer to hands and cause problems (such as when eating). * Game cartridges for the

Nintendo Switch The is a video game console developed by Nintendo and released worldwide in most regions on March 3, 2017. Released in the middle of the Eighth generation of video game consoles, eighth generation of home consoles, the Switch succeeded the ...

are coated with denatonium as a safety feature to deter small children from ingesting them. *Some button cell batteries manufactured by Duracell are coated with a bitterant to discourage accidental ingestion by children.

Examples of bitterants

* Denatonium is used in a variety of applications as an aversive agent. * Sucrose octaacetate * Quercetin * Brucine * Quassin

Bitterness scales

The threshold for stimulation of bitter taste by

quinine Quinine is a medication used to treat malaria and babesiosis. This includes the treatment of malaria due to ''Plasmodium falciparum'' that is resistant to chloroquine when artesunate is not available. While sometimes used for nocturnal leg ...

averages a concentration of 8 μ M (8 micromolar).Guyton, Arthur C. (1991) ''Textbook of Medical Physiology''. (8th ed). Philadelphia: W.B. Saunders The taste thresholds of other bitter substances are rated relative to quinine, which is thus given a reference index of 1. For example, Brucine has an index of 11, is thus perceived as intensely more bitter than quinine, and is detected at a much lower solution threshold. The most bitter substance known is the synthetic chemical denatonium, which has an index of 1,000. It is used as an aversive agent (a bitterant) that is added to toxic substances to prevent accidental ingestion. This was discovered in 1958 during research on

lignocaine Lidocaine, also known as lignocaine and sold under the brand name Xylocaine among others, is a local anesthetic of the amino amide type. It is also used to treat ventricular tachycardia and ventricular fibrillation. When used for local anaesth ...

, a local anesthetic, by MacFarlan Smith of

Gorgie Gorgie ( ) is a densely populated area of Edinburgh, Scotland. It is located to the west of the city centre, and borders Murrayfield, Ardmillan and Dalry, Edinburgh, Dalry. Name The name is thought to be British language (Celtic), Brythonic in ...

Edinburgh Edinburgh is the capital city of Scotland and one of its 32 Council areas of Scotland, council areas. The city is located in southeast Scotland and is bounded to the north by the Firth of Forth and to the south by the Pentland Hills. Edinburgh ...

Scotland Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac ...

Brewery

Beer bitterness scales attempt to rate the perceived relative bitterness of beer. The bitterness of beer is provided by compounds such as isohumulones from

hops Hops are the flowers (also called seed cones or strobiles) of the hop plant ''Humulus lupulus'', a member of the Cannabaceae family of flowering plants. They are used primarily as a bittering, flavouring, and stability agent in beer, to whic ...

used during brewing. The International Bittering Units scale, or simply IBU scale, is measured through the use of a spectrophotometer and solvent extraction a calculation is performed on this absorbance to give a result in IBU. This technique was adopted at the same time as another method based on measuring the concentration (in milligrams per litre;

parts per million In science and engineering, the parts-per notation is a set of pseudo-units to describe the small values of miscellaneous dimensionless quantity, dimensionless quantities, e.g. mole fraction or mass fraction (chemistry), mass fraction. Since t ...

w/v) of IAA isomerized α acids in a beer, causing some confusion among small-scale brewers. The American Society of Brewing Chemists, in the introduction to its methods on measuring bitterness, points out some differences between the results of the two methods: The European Bitterness Units scale, often abbreviated as EBU, is a bitterness scale in which lower values are generally "less bitter" and higher values "more bitter". The scale and method are defined by the European Brewery Convention, and the numerical value should be the same as of the International Bitterness Units scale (IBU), defined in co-operation with the American Society of Brewing Chemists. However, the exact process of determining EBU and IBU values differs slightly, which may in theory result with slightly smaller values for EBU than IBU. IBU cannot be determined by perceived bitterness. For example, the bittering effect of hops is less noticeable in beers with a high quantity of malt, so a higher bitterness is needed in heavier beers to balance the flavour and achieve the same perceived bitterness as compared to a lighter beer. For example, an Imperial Stout may have an IBU of 50, but will taste less bitter than an English Bitter with an IBU of 30, because the latter beer uses much less malt than the former. After around 100 IBU, hop utilization is so poor that the number ceases to be meaningful in regard to taste, although continued hop additions will increase bitterness. Light lagers without much bitterness will generally have 8–20 IBU, while an India Pale Ale may have 60–100 IBU or more.

References

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