Describing the chemical singularity of the Spanish protected designations of origin for virgin olive oils in relation to oils from neighbouring areas

The protected designations of origin (PDOs) have proven to be a successful regulatory framework to protect singular virgin olive oils that have distinctive properties. However, sometimes the registration of new PDOs and the demarcation of the geographical areas associated to them are based on administrative issues rather than objective chemical data. In this work, the chemical compositions of fatty acids, hydrocarbons, alcohols, sterols and methyl sterols have been used to prove the differences between a PDO virgin olive oil and the oils produced in the surrounding areas. Three cases were studied (PDO Estepa, PDO Montoro-Adamuz, and 26 Campina de Jaen) which actually mean three different situations that combine variations in cultivar and pedoclimatic characteristics. The chemical compounds that showed a better ability to classify samples were selected by the Brown-Forsythe test, a particular modification of ANOVA, and this ability was later visualized in a principal component analysis. The oils from PDOs Estepa and Montoro-Adamuz showed clear differences in their chemical compositions, while the oils from Campina de Jaen formed a group of samples which greatly overlapped with the oils from surrounding areas, probably due to the lack of variation in cultivar (Picual) throughout the province of Jaen.