Acetaldehyde is a naturally occurring chemical that is colorless, flammable, and has a characteristic pungent odor. It is miscible with water, alcohol and ether.
Acetaldehyde is found in apples, broccoli, cheese, coffee, grapefruit, grape juice (Concord), grapes, onions, lemons, milk (skimmed and heated), oranges, peaches, pears, pineapple, raspberries, strawberries, peppermint oil, anise, cooked beef and cooked chicken. It is also found in car exhaust, perfumes, flavors, aniline dyes, synthetic rubber, wood products and in the gut as a byproduct of Candida.
It is used in the manufacture of perfumes, food flavorings, aniline dyes, plastics, paint and various synthetic substances. Acetaldehyde is also used as a solvent in the rubber, tanning, and paper industries, as a fruit and fish preservative, as a flavoring agent, for hardening gelatin, as a denaturant for alcohol and in fuel compositions.