A plant does not hand you its smell. You have to get it out, and every way of doing so loses something.
This is the most basic fact in the aromatics trade, and also the one least often stated on labels.
Nine ways, nine results
Distillation accounts for most of the world’s output, and it comes in three forms, not one. Water distillation soaks the material directly in boiling water — this is the copper pot of village workshops. Water and steam distillation sets the material on a grid above the water. Direct steam distillation uses steam from a separate boiler.
All three work at around a hundred degrees, but they differ in whether the material touches boiling water — and that difference shows up on an analysis. All three carry off the molecules light enough to travel with the steam, and leave behind everything too heavy or too fragile.
Cold pressing is the only method without heat, but it works only for citrus peel, where the oil lies just below the surface.
Solvent extraction takes even the heavy molecules that heat would destroy, at the cost of solvent traces at the parts-per-million level.
Supercritical CO2 leaves no trace, but the equipment is expensive and the broad extraction sometimes drags unwanted waxes along too.
Enfleurage gives the result closest to the living flower of all nine methods, and is so labour-intensive it is no longer commercially viable.
Hot oil infusion is the oldest method and still alive in Vietnamese kitchens, producing a scented oil rather than an essential oil.
The principle nobody states on the label
The method is part of the product, not a technical detail.
Cold-pressed orange oil and distilled orange oil are two different things. The first smells like a real orange; the second smells like the memory of an orange. Both are pure orange oil, and both are correctly named.
A label saying orange oil without stating the method is missing half the information.
How to choose
There is no best method. There is the method that suits each raw material and each purpose.
For citrus peel, cold pressing is almost always the right choice. For white flowers, solvent extraction is the only way to keep the true smell. For roots and woods, long distillation or CO2 both give good results. For kitchen spices, hot oil infusion gives something usable at once without dilution.
The next lesson takes jasmine as a detailed example of where choosing the wrong method leads.
Scenting is the ninth method, and the only one in which the final product is the carrier itself rather than something extracted from it. Dry tea absorbs the smell of flowers over several rounds of scenting; what you receive is tea, not an essential oil.
Set all nine side by side on the comparison page to see the axes of temperature and solvent, and what each method loses.