Garlic oil is the volatile oil (essential oil) derived from garlic. It is typically prepared using steam distillation, whereby crushed garlic is steamed with the resultant condensation containing the oil.
Garlic oil contains volatile sulphur compounds such as diallyl disulphide, which is the “most abundant constituent” of essential garlic oil. Steam-distilled garlic oil typically has a pungent odour and a yellow-brownish coloration. Its odour has been attributed to the presence of diallyl disulphide. To produce around 1 g of pure steam-distilled garlic oil, around 500 g garlic is required.
Steam-distilled garlic oil has around 900 times the strength of fresh garlic, and around 200 times the strength of dehydrated garlic.