Characterization of Olive Oils Used as Medium in Canned Fish

Background: The assessment of the quality extra virgin olive oils used as liquid medium in canned fish together with the levels of phenolic compounds is very important in order to evaluate if the higher price of the extra virgin olive oil in canned fish in comparison with fish in olive oil is justified. Objective: The aim of the study was to identify and quantify the phenolic compounds in processed food such as canned fish in order to assess the added value of extra virgin olive oil used as a liquid medium in canned fish. The authenticity of olive oils used as liquid medium in canned fish was assessed by determination of sterol composition, fatty acid composition and content of stigmastadiens. Materials and Methods: Various different manufactures Slovenian The content of oil was first separated from fish and then immediately analyzed for sterol composition and concentrations, fatty acid composition, stigmastadiens levels, acidity, peroxide number and phenolic compounds composition and content. Conclusion: labelling the packaging. of


Introduction
Fish products are often sold together with vegetable oil such as olive oil. Lately, the market also offers fish products with extra virgin olive oil. Olive oil which contains 98-99% triacylglycerols and a high proportion of stable oleic acid can provide combined with fish meat the recommended ratio between n-3 and n-6 fatty acids [1][2][3].
Olive oil can also represent a significant source of antioxidants such as vitamin E and a source of various phenolic compounds that are not present in other foodstuff [4,5]. Antioxidants such as phenolic compounds in olive oil can not only have a protective role on human health [6], but they can also protect the important compounds such as unsaturated fatty acids against oxidation [7]. However, due to the high costs of olive oil production, the frauds such as adding cheaper oils to olive oil can be found. Moreover, products such as fish products in olive oil, where fish meat may cover the specific taste of olive oil, can often be the target of frauds. Due to the increased possibility of frauds, the market norms for olive oil compared to other oils are very strict. However, olive oils sold together with fish meat are not addressed. According to Commission Regulation Objective: The aim of the study was to identify and quantify the phenolic compounds in processed food such as canned fish in order to assess the added value of extra virgin olive oil used as a liquid medium in canned fish. The authenticity of olive oils used as liquid medium in canned fish was assessed by determination of sterol composition, fatty acid composition and content of stigmastadiens.

Materials and Methods:
Various fish products in olive oil or extra virgin olive oil were sampled randomly from different manufactures on the Slovenian market. The content of oil was first separated from fish and then immediately analyzed for sterol composition and concentrations, fatty acid composition, stigmastadiens levels, acidity, peroxide number and phenolic compounds composition and content.

Conclusion:
Oil in canned fish products corresponded to the declared labelling on the packaging. However, the levels of determined phenolic compounds were much lower and the composition of phenolic compounds was different compared to the usual extra virgin olive oil from Slovenian producer. oxidation, the main aim of the study was to identify and quantify the phenolic compounds in processed food such as canned fish in order to assess the added value of extra virgin olive oil used as a liquid medium in canned fish. In addition, the authenticity of olive oils used as liquid medium in canned fish available on the Slovenian market was assessed by the determination of sterols composition and content, fatty acid composition and the levels of stigmastadiens. As far as we are concerned this is the unique study that involves the determination of phenolic compounds in olive oil from processed food available on the Slovenian market by high performance equipment. The results obtained in this study will help the testing olive oil laboratories to better evaluate the quality and potential frauds of extra virgin olive oil added to processed food such as canned fish.  [8]. The fatty acid composition of olive oil was determined by in situ transesterification with GC-FID [9]. The content of stigmastadienes in olive oils samples were determined by the column and capillary gas chromatography [10]. The determination of acidity and peroxide number was carried out according to the standard methods [11,12]. The phenolic composition of olive oils was determined by high performance liquid chromatographymass spectrometry (HPLC-ESI-QqQ) [13,14] and the unknown compound present in high levels was additionally identified by HPLC-ESI-qTOF [15].

Conclusion
Even though by the quality parameters it is clear that oil in canned fish products corresponds to the declared labelling on the packaging, the levels of determined phenolic compounds were much lower than it is expected for extra virgin olive oils. In addition, the composition of phenolic compounds was different compared to the usual extra virgin olive oil from Slovenian producer.