Advances in DNA extraction for detecting extra-virgin olive oil adulterations

This chapter aims at examining the evolution and the critical points of DNA extraction techniques for detecting extra-virgin olive oil adulteration. DNA can be extracted either directly from oil, or from the cellular pellet recovered after oil centrifugation. Whenever possible, fingerprinting DNA obtained from sediment-rich unfiltered oil should be preferred, for higher amounts that make the extraction procedure easier compared to filtered oil. The DNA extraction method, however, is developed in the framework of an integrated approach: each protocol takes into account the type of marker that has to be analyzed on the extracted DNA. Up until now, several protocols to extract DNA from olive oil have been developed, based on liquid-liquid or solid-phase extraction. In addition, many commercial kits for DNA micro-extraction from processed food are currently available and help researchers in routine analyses. There is now undoubtedly the need of standardizing and validating a definitive and unique protocol of DNA extraction from olive oil.