Sterols and triterpene diols in olive oil as indicators of variety and degree of ripening
Results demonstrated that sterols and triterpene diols can be used as indicators of variety and degree of ripening among virgin olive oils. The majority of indicators are stable after a 12-month storage
Sterols and triterpene diols are important constituents of olive oil and constitute the major proportion of its unsaponifiable fraction. Previous studies have shown that each oily fruit has a characteristic profile of these compounds which makes its determination an important tool in authenticating the genuineness of olive oil and detecting adulteration, e.g. in the case of detecting a mixture with hazelnut oil.
For this reason, the content of sterols and triterpene diols in olive oil is regulated by the legislation of the European Union (EEC, 1991) and by the trade standard applying to olive oils and olive–pomace oils set by the International Olive Council (IOC, 2011). Additionally, the importance of sterols is manifested through the exhibition of certain health benefits which significantly contribute to the nutritional value of olive oil. It has been reported that these compounds have hypocholesterolemy, anti-inflammatory and anti-carcinogenic effects.
Sterols and triterpene diols in olive oil as indicators of variety and degree of ripening derived from three olive varieties and produced at three different harvesting periods were studied.
In order to test the stability of the proposed indicators, oils obtained were stored for 12 months at three different temperatures.
Thirty-six samples in total were subjected to GC analysis and results were processed by multivariate chemometric methods (MANOVA, PCA, and SLDA).
Campesterol, β-sitosterol, Δ7-campesterol/Δ5,24-stigmastadienol, clerosterol, uvaol, and campestanol/Δ7-avenasterol were established as the indicators of variety of fresh oils, while when stored oils were included in the model, the final three compounds were substituted by 24-methylene-cholesterol/stigmasterol.
The most important variables for differentiating fresh oils according to degree of ripening were Δ7-campesterol/β-sitosterol, uvaol/stigmasterol, clerosterol/Δ5-avenasterol and sitostanol/uvaol, while stored oils were differentiated by campestanol/stigmasterol, erythrodiol, stigmasterol/Δ7-campesterol, Δ5-avenasterol, 24-methylene-cholesterol/β-sitosterol and 24-methylene-cholesterol.
Results demonstrated that sterols and triterpene diols can be used as indicators of variety and degree of ripening among virgin olive oils.
Marina Lukić, Igor Lukić, Marin Krapac, Barbara Sladonja, Vlasta Piližota, Sterols and triterpene diols in olive oil as indicators of variety and degree of ripening, Food Chemistry, Volume 136, Issue 1, 1 January 2013, Pages 251-258, ISSN 0308-8146