Food is deliberately denatured when a substance, known as a denaturant, is added to render the food unpleasant to consume or poisonous. Aversive agent

Aversive agent

Aversive agents are unpleasantly flavored substances added to poisonous household goods in order to discourage children from consuming the poisonous household products. Aversive agents are not intended to be harmful, only unpleasant...

s—primarily bitterant

Bitterant

A bitterant is a chemical that is added to a product to make it smell or taste bitter. Bitterants are commonly used as aversive agents to discourage the inhalation or ingestion of toxic substances.-Examples of use:...

s and pungent agents—are used to produce an unpleasant flavor. For example, the bitterant denatonium

Denatonium

Denatonium, usually available as denatonium benzoate and as denatonium saccharide, is the bitterest chemical compound known; with bitterness thresholds of 0.05 ppm for the benzoate and 0.01 ppm for the saccharide.It was discovered in 1958 during research on local anesthetics by Macfarlan...

 might be added to food used in the laboratory

Laboratory

A laboratory is a facility that provides controlled conditions in which scientific research, experiments, and measurement may be performed. The title of laboratory is also used for certain other facilities where the processes or equipment used are similar to those in scientific laboratories...

, where the food is not intended for human consumption. A poison

Poison

In the context of biology, poisons are substances that can cause disturbances to organisms, usually by chemical reaction or other activity on the molecular scale, when a sufficient quantity is absorbed by an organism....

 may be added as an even more powerful deterrent. For example, methanol

Methanol

Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...

 is added to ethanol

Ethanol

Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

 to produce denatured alcohol. The addition of poisonous methanol renders denatured alcohol unfit for consumption. Thus denatured alcohol is not subject to the taxes alcoholic beverages are subject to.