Olive oil is produced mainly in the Mediterranean countries. The delicate flavour and the health benefits associated with olive oil along with the low level of purification and processing have produced a market where the oil commands a high price. As a result of this there is an opportunity for fraudulent substitution or admixing of olive oil with cheaper edible oils, and therefore a need for techniques that can identify and quantify the presence of other edible oils in olive oil.
Current methods are based on analysis of the fatty acid composition of the oils, however some edible oils (eg hazelnut oil) can not be distinguished from olive oil using these methods due to their high oleic acid content.
This study aims to investigate two alternative methods for detecting adulterant oil in olive oil using the steroidal hydrocarbon content of the samples. The first method involves producing an n-alkane pattern for the oils using gas chromatography with flame ionisation detection (GC-FID). This should produce unique patterns for the different types of edible oils. The second method will look at the sterene content using GC mass spectrometry. These two techniques in combination should be able to identify and quantify any adulterant oils in a sample of olive oil.
The study will begin by analysing the n-alkane content of crude and refined hazelnut oils. These oils will then be analysed using the sterene method utilising the GC-mass spectrometry.
The virgin olive oil and refined olive oil will then be spiked with known levels of crude or refined olive oil at level of between 10% w/w - 0.5% w/w. These oils will then be tested with the two techniques to obtain data on the techniques ability to identify adulterant.
The data produced by the study will be statistically analysed to assess the reliability of the technique in identifying adulterant oils in olive oil. This will also allow a limit of measurement to be detected.
<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>.