To assess the quality of the cold-pressed essential oil of bergamot, the following specifications are carried out:

organolectic examination, specific weight at 15, optical rotation at 15 optical rotation refractive index of refraction of the first tenth distilled, acid number of esters, aldehydes, alcohol, evaporation residue, solubility in alcohol.

Complete judgement of the quality of the essence also takes into account some instrumental definitions based above all on vapour-phase chromatography (VPC), on thin-layer chromatography (TLC), on high resolution liquid-liquid chromatography (HPLC), on the spectrophotometry in UV and IR.

These findings, properly conducted make it possible to investigate the depths of the composition of the essential oil and reveal the possible presence of aldulteration and contamination.

On examining the chemical composition, three principal groups of consituents are distin-guishable: oxygenated compounds (aldehydes, ketones, alcohol and esters) from which the typical perfume which makes up the bouquet of the essence is mostly derived, terpenes and sesquiterpènes, components of the non-volatile residue. Terpenes and sesquiterpenes constitute a sort of ballast that gives no olfactory contribution.

The elimination of terpenic hydrocarbons makes way for the terpeneless oil, the elimination of the terpenic and sesquiterpenic hydrocarbons gives rise to sesquiterpeneless oils. These concentrated oils are more soluble in alcohol and more stable even if they are partly lacking in some true-to-nature olfactory notes that recall the freshness of the original fruit.