Volatile oil content is the quantity of essential oil present in a dried herb or spice, determined by steam distillation and expressed as volume per unit mass, serving as the primary index of aromatic strength in trade specifications.
In trade practice
The European Pharmacopoeia and ISO spice standards describe the steam distillation method used to determine volatile oil content; buyers reference these methods in purchase specifications to ensure comparable results. Suppliers test each production lot and report the result on the certificate of analysis. Low values typically indicate over-mature raw material, excessive drying temperatures or prolonged storage, all of which degrade volatile compounds. QA teams at intake may retest against the declared figure, particularly for high-value spices such as coriander, caraway or dill.
In a specification
A spice specification states the minimum volatile oil content as a volume-per-mass figure, the distillation method reference and whether the limit applies to the lot average or to individual samples.