Cultivar and growing area effects on minor compounds of olive oil from autochthonous and European introduced cultivars in Tunisia.

BACKGROUND: Antioxidant profile and volatile compounds were characterized in three virgin olive oils from European countries introduced and cultivated under the same orchard conditions in comparison to some autochthonous cultivars planted in different areas of Tunisia. RESULTS: Significant differences were observed between the oils. α-Tocopherol content is more important in autochthonous Tunisian cultivars (cvs), higher (400 mg kg−1) than in European cvs. Total phenols showed that Chetoui cv. (grown in Zaghouan) had the highest level (446 mg kg−1), followed by Koroneiki (403 mg kg−1 ) and Chetoui cvs (grown in Beja) (398 mg kg−1). Koroneiki oils had the highest content of (3,4-dihydroxyphenyl)ethanol and (p-hydroxyphenyl)ethanol (20.5 and 43.5 mg kg−1, respectively), whereas (3,4-dihydroxyphenyl)ethanol was not detected in Arbequina, Arbosana or Chemlali cvs (grown in Sahel). Chetoui cv. presented the highest content of dialdehydic form of decarboxymethyl elenolic acid linked to (3,4-dihydroxyphenyl)ethanol (171 mg kg−1), whereas Chemlali (Sahel) cv. had the lowest content (29.6 mg kg−1). The volatile compounds showed an increase in C6 compounds and decrease in pentene isomers in olive oils from varieties cultivated in other growing areas. CONCLUSION: Virgin olive oils studied demonstrate that the differences in phenols, tocopherol levels and volatile profiles may be explained by genetic factors and geographic areas, particularly altitude.