Determination of Biophenols in Olive Oil

Vegetable oils contain various antioxidants, including vitamin E and unsaturated fatty acids. Some of these oils, especially olive oil, contain another group of antioxidant – phenolic compounds. The health benefits from the phenolics have recently been published with the rising recommendation of communicating these effects on food labels. As an official testing method is unavailable from AOCS and AOAC, we developed an HPLC method based on the biophenol method of the International Olive Council. Many analytical standards are commercially unavailable for biophenols, and neither retention time nor capacity factor can be used in chromatograms for biophenol identification. Therefore we identified a set of available standards with different retention times to spread across the chromatogram in addition to an internal standard. The biophenol profile can thus be established referring to these standards. More than 20 biophenols were included in this method. Different brands of olive oil and several types of vegetable oils were sampled and tested. Extra virgin olive oil was found to have the highest content while fewer biophenols were found in processed olive oil and other vegetable oils. As for the other vegetable oils different biophenol profiles were also observed. This method has great potential in olive oil authenticity testing, and in quality control to differentiate substandard olive oils.