Chapter 49 - Olive Oil Adulteration with Hazelnut Oil and Analytical Approaches for Its Detection

Abstract

Adulteration of olive (Olea europaea) oil with vegetable, seed, or nut oils has become a serious problem for regulatory agencies, consumers, oil producers, and oil importers. Admixtures of olive oil with hazelnut (Corylus spp.) oil, in particular, represent one of the most recent challenges facing scientists and regulatory bodies. Although hazelnut oil is not associated with some of the health risks attributed to some of the other low-quality oils used to adulterate olive oil, the difference in economic value between the two oils causes an estimated loss of 4 million euros per year for countries in the European Union. In addition, the dietary intake of health-benefiting components found naturally in virgin olive oil (e.g. polyphenols, sterols, tocopherols) can be greatly reduced following consumption of oils adulterated with low-quality refined hazelnut oils. Detection of hazelnut oil in admixtures with olive oil has always been very difficult to confirm due to very similar chemical profiles exhibited by the two oils, especially in terms of triacylglycerols and fatty acids. Numerous chemical approaches have been proposed over the last 15 years that are able to detect various hazelnut oil/olive oil blends. Profitable olive oil adulteration by hazelnut oil, as with most other edible oils, can only be effected by one of three ways: virgin (also termed crude or pressed) hazelnut oil into virgin olive oil, refined hazelnut oil into virgin olive oil, and refined hazelnut oil into refined olive oil. This chapter presents an overview of the modern analytical approaches (proposed over the last two decades or so) and the current state of knowledge in each of the three adulteration scenarios.