Detection of hazelnut oil in virgin olive oil by assessment of free sterols and triacylglycerols

Free sterols were evaluated as factors for discriminating between genuine v irgin olive oil and hazelnut-mixed virgin olive oil. Numeric analyses of th e results amplified the differences between groups. The application of this method to virgin olive oil samples and their mixtures with 10% hazelnut oi l distinguished between genuine and nongenuine virgin olive oil with statis tical certainty. Triacylglycerol analysis was tested for the same purpose b y using parameter Delta ECN42, but although it possessed a discriminating c apacity, it alone could not distinguish the aforementioned groups with suff icient certainty. Free Delta7-sterols data were combined with Delta ECN42 d ata into a single discriminating function to improve differentiation and br ing more ruggedness, and for detection of low amounts (10%) of hazelnut oil in virgin olive oil. In fact, the values obtained by addition of Delta7-st erol data and Delta ECN42 data showed a higher discriminating capacity than single parameters. In a single operation the method produced all the oil f ractions necessary for analysis of free sterols and triacylglycerols with E CN42. Solid-phase extraction was applied in substitution of traditional chr omatography on a silica column.