Fatty Acid Profiling of the Main Tissues of Spanish Olive Fruit: Effect of the Oil Extraction Method

The aims of the present study were as follows: (1) study of the extraction efficiency of the methods to obtain extra virgin olive oil and pomace oil, and the fatty oil composition provided by each tissue and the whole fruit using both methods; (2) characterisation of the oil obtained by each extraction method according to quality parameters; and (3) development of chemometric models able to explain the differences between the oils obtained from the different extraction procedures, olive varieties or fruit tissues. With these objectives in mind, eight fruit varieties (i.e. arbequina, frantoio, hojiblanca, lechin from Sevilla, manzanilla, ocal, picual and picudo) from the same geographical area, harvested when the maturation was complete and the fatty acids content was at a maximum, were used. Oils from the whole fruit and from each of its main tissues (i.e. ectocarp, mesocarp, endocarp, and kernel) were sequentially extracted by the two methods based on principles similar to those used in the oil industry: pressure + centrifugation for extra virgin oil extraction and organic solvents for pomace oil. The oils thus obtained were weighed to know the oil richness of the fruit and that of each separate tissue, and also to determine the efficiency of each extraction method. Then, the fatty acids were subject to derivatisation, individual separation of the products by gas chromatography and identification-quantitation by tandem-mass-spectrometry. The results thus obtained (fatty-acid profile of the oil from each tissue obtained with each oil-extraction method and from each olive-fruit variety) were subject to statistical studies to fulfill the aims of the research.