Caprylic acid is the common name for the eight-carbon saturated fatty acid known by the systematic name octanoic acid. It is found naturally in the milk of various mammals, and it is a minor constituent of coconut oil and palm kerner oil. It is an oily liquid that is minimally soluble in water with a slightly unpleasant rancid-like smell and taste.
Caprylic acid is used commercially in the production of esters used in perfumery and also in the manufacture of dyes. Caprylic acid is also used in the treatment of some bacterial infections. Due to its relatively short chain length it has no difficulty in penetrating fatty cell wall membranes, hence its effectiveness in combating certain lipid-coated bacteria, such as Staphylococcus aureus and various species of Streptococcus.
Caprylic acid is an antimicrobial pesticide used as a food contact surface sanitizer in commercial food handling establishments on dairy equipment, food processing equipment, breweries, wineries, and beverage processing plants. It is also used as disinfectant in health care facilities, schools/colleges, animal care/veterinary facilities, industrial facilities, office buildings, recreational facilities, retail and wholesale establishments, livestock premises, restaurants, and hotels/motels. In addition, caprylic acid is used as an algaecide, bactericide, and fungicide in nurseries, greenhouses, garden centers, and interiorscapes on ornamentals. Products containing caprylic acid are formulated as soluble concentrate/liquids and ready-to-use liquids. For ghrelin to have a hunger-stimulating action on a hypothalamus, caprylic acid must be linked to a serine residue at the 3-position of ghrelin. To cause hunger, it must acylate a -OH group. Other fatty acids in the same position have similar effects on hunger.
The octanoic acid breath test is used to measure gastric emptying. Some potential benefit is possible from administration of octanoic acid for patients with essential tremor. The acid chloride of caprylic acid is used in the synthesis of perfluorooctanoic acid. Caprylic acid is taken as a dietary supplement within alternative medicine. It is believed to suppress fungal infections within the gut, notably candida albicans infection.