engleski

Determination of bioactive antioxidants in extra virgin olive oil from Croatia

Introduction. Free radicals/reactive oxygen species (ROS) are generated from both endogenous and exogenous sources. Most of the body macromolecules, such as lipids, proteins, DNA and carbohydrates are susceptible to damage by ROS. Extra virgin olive oil (EVOO) could be considered as example of a functional food, with a variety of components that may contribute to its overall therapeutic characteristics. EVOO contains at least 30 phenolic compounds. The major phenolic compounds are oleuropein derivatives, based on hydroxytyrosol which are strong antioxidants and radical scavengers. The most widely employed methods for evaluating the total phenolic content (TP) of extra virgin olive oil extract (EVOOE) are the Folin–Ciocalteu (FC) colorimetric assay. Another colorimetric assay that could be used is the method with sodium molybdate, specific for the quantification of o- diphenols. The antioxidant activity of these extract can be estimated by reaction with the stable radical 2, 2-diphenyl-1-picrylhydrazyl (DPPH). Materials and methods. Three different EVOO from Istra (Bjelica, Buža and Žižolera) and from Ugljan island have been analysed in this study. The TP content was determined by the FC method according to the analytical protocol. The concentration of o-diphenols in the EVOOE was determined with sodium molybdate assay. The antioxidant activity of EVOOE was performed using the stable radical DPPH according to the procedure with some modifications. Results. The concentration of TP and o- diphenols in extracts was expressed as mg gallic acid equivalent (GAE) per kg of EVOO (Fig. 1.). Gallic acid served as a standard for the preparation of the calibration curve. The antioxidant activity expressed as EC50 value denotes the concentration leading to 50% reduction of the initial DPPH concentration. Conclusion. Analysed EVOO derived from Croatia (Istra and Ugljan island) have concentration of TP, o-diphenols and EC50 values comparable to those in literature which provide good properties of oil in disease prevention

Olive oil ; total phenols ; o-diphenols ; antioxidant activity

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