Quantitation of oleuropein and hydroxytyrosol in Greek edible olives
Table olives from Olea europaea L. are a traditional Greek product and a very important component of the Mediterranean diet . Olive fruits are sources of biophenols such as oleuropein and hydroxytyrosol. Ten commercial types of Greek table olives were studied and several differences were observed among them. A method for the extraction and quantitation of oleuropein and hydroxytyrosol in olive fruits was developed. Hydroxytyrosol was found in the majority of the types of olives. Green „tsakistes“ contained the highest quantity of hydroxytyrosol (2mg/fruit) followed by „chondrolies“ and „mavrolies“. However, the olives of Kalamata were considered to have the lowest level of hydroxytyrosol. From the other hand, oleuropein could not be found in any of the olives, which were examined except Throuba Thassou. Only traces of oleuropein were found in „chondrolies“ and „mavrolies“ while in contrast Throuba Thassou were rich in oleuropein (1.2mg/fruit) and in other phenolic compounds. It is the first time in the research on edible olives, that prominent quantity of oleuropein is observed and this is due to the particular type of Throuba Thassou and also due to the specific way of processing . The cultivated variety, the specific process applied on the fruits and especially their stay in brine have significant consequences in the concentration of polyphenols in the table olives . In conclusion, the presence of hydroxytyrosol in all the types of edible olives examined and of oleuropein in Throuba Thassou, reinforce the opinion that the addition of edible olives in our diet is necessary and in combination with olive oil, they can provide important quantities of natural antioxidants.
Acknowledgement: The project was funded by the General Secreteriat for Research and Technology of Greece (Program EPAN TP-27) References: 1. Simopoulos, A. (2001)J. Nutr. 131: 3065S-3073S
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