9 - Bioactive Phenolic Compounds from Olea europaea: A Challenge for Analytical Chemistry

Abstract

The Mediterranean diet and its basic constituent, olive oil, are today of great interest due to their healthy virtues. Among other fat sources, olive oil, especially Extra Virgin Olive Oil (EVOO) and Virgin Olive Oil (VOO), is unique due to a characteristic phenolic composition that is at least in part the key of its beneficial properties. Phenolics are important because they are natural antioxidants that contribute to the quality and organoleptic features of EVOOs. Moreover, the amount of phenolic compounds and their profile change during fruit maturity, and this is a determinant for the biological properties of the fruit and the oil produced. Thus, the determination of these minor compounds is a challenge for the analyst, who may combine hyphenation of chromatography and electrophoresis techniques with Ultraviolet (UV), fluorescence, and Mass Spectrometry (MS) detection, as well as fluorescence, Infrared (IR) and Nuclear Magnetic Resonance (NMR) spectroscopies, and ambient MS. This set of techniques permits detection of phenolic components directly in olives and olive oil without or with poor pretreatment. High-resolution spectroscopy coupled further to the facilities of computerized mathematical and statistical processing of the data has found interesting applications in this field. Electrochemical-based techniques are also used for the detection of phenolic compounds, but their application in the analysis of olive and olive oil phenolics is not as wide. This chapter reviews most of the advances in extraction methods, Gas (GC) and Liquid Chromatography (LC), Capillary Electrophoresis (CE), the main separation techniques, and the detection strategies, including spectrophotometry, MS, and NMR spectroscopy. It discusses the application of these methodologies to determine phenolic compounds in olive fruit and olive oil and their metabolites in biological samples, which is based mainly on literature published in the last 5 years.