Garlic oil is the volatile oil derived from garlic.[1] It is usually prepared using steam distillation and can also be produced via distillation using ether. It is used in cooking and as a seasoning, a nutritional supplement, and also as an insecticide.
Garlic oil is typically prepared using steam distillation,[1] where crushed garlic is steamed with the resultant condensation containing the oil.[2] Garlic oil contains volatile sulfur compounds such as diallyl disulfide, a 60% constituent of the oil.[1] Steam-distilled garlic oil typically has a pungent and disagreeable odor and a brownish-yellow color.[3] Its odor has been attributed to the presence of diallyl disulfide.[1][3] To produce around 1 gram of pure steam-distilled garlic oil, around 500 grams of garlic is required.[2] Undiluted garlic oil has 900 times the strength of fresh garlic, and 200 times the strength of dehydrated garlic.[3]
Ether can also be used to extract garlic oil.[2] A type of garlic oil involves soaking diced or crushed garlic in vegetable oil, but this is not pure garlic oil; rather it is a garlic-infused oil.[2]
Garlic oil is used as a nutritional supplement, and is sometimes marketed in the form of capsules, which may be diluted with other ingredients.[1][2] Some commercial preparations are produced with various levels of dilution, such as a preparation that contains 10% garlic oil.[3] Herbal folklore holds that garlic oil has antifungal and antibiotic properties,[4] but there is insufficient clinical research confirming such effects.[1] It is also sold in health food stores as a digestive aid.[1][5]
It can be used as an insecticide, diluted with water and sprayed on plants.[4][6]
Stabilized garlic flavor blend is a proprietary mixture of dehydrated garlic powder infused with garlic oil, which increases the flavor of the garlic powder.[7]
Common adverse effects of consuming garlic, garlic oil, and garlic supplements are breath and body odor, abdominal pain, nausea, vomiting, and other symptoms of gastrointestinal disorders.[1] Garlic oil consumption may have anticoagulant effects in some people, causing bleeding, and may interfere with prescription drugs.[1]
Garlic oil has been assessed in laboratory and preliminary clinical research for its potential to affect human health, with inconclusive results, as of 2016.[1]
Garlic-flavored oil is produced and used for cooking and seasoning purposes, and is sometimes used as an ingredient in seasoning mixtures.[2][3] This differs from essential garlic oil, and typically involves the use of chopped, macerated or crushed garlic placed in various vegetable oils to flavor the oil.[1]