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Phenolic profile and antioxidant activity of virgin olive oil from cv. Drobnica

One of the most important antioxidants in virgin olive oil (VOO) are phenolic compounds. The amount of phenolic substances present in VOO, as well as the fatty acid composition, is related to the health beneficial effects that make VOO a very valuable and appreciated commodity. The level of these substances is a very important parameter in the evaluation of VOO quality since phenols are strictly related both to the oil’s resistance to oxidation because of their antioxidative properties. The aim of the present study was to define parameters for the characterization, polyphenolic composition and related antioxidative properties of monovarietal olive oil from cv. Drobnica grown in Dalmatia (Croatia). We also examined the antioxidant activity, total antioxidant capacity and oxidative stability of Drobnica’s oil. Besides several qualitative parameters (free acidity, peroxide value and UV spectrophotometric indices), the analyses of major (fatty acids) and minor components (phenolic fraction and their antioxidant power evaluated by ABTS●+ and electrochemical test) were also carried out. Radical scavenging activity of phenolic extracts was performed by ABTS+ and DPPH methods. An amperometric flow injection method (FIA) was used for the evaluation of the antioxidant power (AOP) of the phenolic extracts of the oil samples. The evaluation of correlation coefficients between parameters DPPH, ABTS, AOP and certain fatty acids and phenolic groups were performed. Olive oil from Drobnica showed high proportion of oleic and palmitic acid. Stable 18:1/18:2 ratio leads to conclusion that this oil has pretty high oxidative stability. Moderate positive correlation between DPPH and linoleic acid was detected, as well as moderate positive correlation between DPPH and the ratio of oleic and linoleic acids. The positive correlation was detected between DPPH and secoiridoides derivates.

virgin olive oil; phenols; fatty acids; antioxidant activity

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