engleski

Trace elemental characterization of olive oils derived from oblica variety

Olive oil is widely used fruit oil especially in the Mediterranean region. Its Olive oil is widely used fruit oil especially in the Mediterranean region. Its flavour as well as its specific chemical composition including high content of monosaturated fatty acids makes it attractive for the use in cooking. Furthermore olive oil is used for producing cosmetics, pharmaceuticals, and soaps, and as fuel for traditional oil lamps. More than 1000 varieties of the olive trees used for olive oil production are grown worldwide. The main variety at the Adriatic coast is Oblica, an autochthonous Dalmatian variety, the most frequently variety in Dalmatian olive-groves. The determination of organic parameters, such as acidity, peroxide value and specific absorptions in the UV region is the basis for the definition of oil quality, and thus widely performed. Although the inorganic analysis of edible oil was neglected, the content of trace and ultra trace elements provides a lot of information on the oil. The inorganic patterns of edible oils can serve as a basis geographical characterization of oils as well as for adulteration detection. Since the importance of Oblica variety in Croatia is very high, the objective of the present research work was the elemental characterization of olive oils derived from Oblica variety. All oils analyzed were confirmed as extra-virgin oils according to their free acids, the peroxide value as well as the K-numbers (K232, K270, dK). They were produced in two different ways, pressing and centrifuguation. The concentration of trace and ultra trace elements were determined by inductively coupled plasma - optical spectrometry (ICP-OES) after acidic microwave assisted digestion. The investigation was focused on 20 elements, namely, Al, As, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, Pb, Se, Si, Sn, V, and Zn. In all oils analyzed the concentrations of As, Cd, Co, Cr, Mn, Mo, Pb, and V were below the limit of detection (LOD). The mode of production is reflected in the inorganic composition of olive oils. Oils produced in the classical way of pressing exhibit higher concentrations of Cu and Fe. Si (approx. 7 µ ; ; g g-1) was found only in these samples, whereas in oils derived by centrifugation the Si contents were below the LOD. Whilst Ni was found in the range of 0, 3 up to 0, 4 µ ; ; g g-1 in oils from centrifugation, no Ni could be detected in pressed samples Since these four elements depend on the way of production, their concentrations can not be used for characterizing the Oblica variety. The contents of Al, Ca, K, Mg, Na, Se, Sn, and Zn were in the ranges from 0, 02 – 0, 5 ; 0, 8 – 11 ; 0, 1 – 2, 5 ; < LOD – 0, 2 ; 2, 7 – 4, 2 ; 0, 6 – 2, 9 ; < LOD – 4, 8 ; and 2, 5 – 4, 0 µ ; ; g g-1 oil, respectively.

olive oil; Oblica variety; trace elements; metals; inductively coupled plasma – optical emission spectrometry

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