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The detection of unrefined hazelnut oil in virgin olive oil is a difficult problem due to similarities in the triacylglycerols, fatty acids and tocopherols of the two oils. One promising approach is to detect pressed hazelnut oil by the analysis of the volatile component (E)-5-methylhept-2-en-4-one.
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In a previous project (Q01015), an alternative approach based on analysis of the non-volatile, polar components of hazelnut oil was developed. Analysis of the polar fraction from virgin olive oil and pressed hazelnut oil by High Pressure Liquid Chromatography (HPLC) showed there were marked differences in the chromatograms of the polar components in the two oils. These differences could be used to detect adulteration of virgin olive oil by pressed hazelnut oil, although further marker peak identification is required.
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The detection of refined hazelnut oil in refined olive oil is even more difficult than the detection of unrefined hazelnut oil, since volatile components are removed during refining. There is currently no method of detecting the admixture of refined hazelnut oil in refined olive oil. It is important to identify which refining steps would still leave marker compounds in refined hazelnut oil that are distinct from those in refined olive oil.
The following approach will be taken to identify a putative marker compound in unrefined hazelnut oil, and then investigate detection of possible adulteration of refined olive oil with refined hazelnut oil.
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1. Collection of authentic samples of unrefined hazelnut oil from companies that press the oil.
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2. Fine tuning of extraction procedure; isolation and characterisation of the marker compound from samples of unrefined hazelnut oil
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3. Ring test of the detection of unrefined hazelnut oil in virgin olive oil by six independent analytical companies
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4.Determination of the variability of the marker compound in authentic samples of unrefined hazelnut oil
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5. Refining of hazelnut oil and olive oil. Analysis of residual polar components in the refined oils and assessment of the possibility of using a residual polar component to detect refined hazelnut oil in refined olive oil.</ul>
<p>Find more about this project and other FSA food safety-related projects at the <a href="http://www.food.gov.uk/science/research/" target="_blank">Food Standards Agency Research webpage</a>.