Changes in Waxes and Ethyl Esters Contents during Green Spanish-style Table Olive Processing
Antonio López-López, Amparo Cortés-Delgado, Alfredo Montaño, Antonio Garrido-Fernández, Instituto de la Grasa (AECSIC), Sevilla, Spain

The waxes and ethyl esters contents are two of the parameters included in the EU regulation for the classification of olive oils (Commission Implementing Regulation (EU) 1348/2013). The hydrolysis of triacylglycerols contributes to the generation of waxes and the reaction of free fatty acids with ethanol produces ethyl esters. Therefore, the contents of these parameters increase as the oil deterioration is higher. The changes in the waxes and ethyl esters contents in the fats from Manzanilla and Hojiblanca olives, processed as green Spanish-style, were studied according to processing steps. Total waxes (considered as C40+C42+C44+C46) and C42+C44+C46 were always higher in the oils from Manzanilla but were not affected by processing. In this study, the C42+C44+C46 sum was always below the limit established in the EU regulation for extra virgin olive oil (EVOO). Therefore, the green Spanish-style table olives have waxes contents in fat comparable to those in EVOO. The relative low proportion of waxes in the oils from green Spanish-style olives (very far below the limits for EVOO) is a good indicator of the relative soft processing of this product and the high protection that the flesh structure and composition offer to the olive fat. The ethyl esters increases during processing, and their overall contents in the final products were slightly above the limit established in the EU regulation for EVOO ( 30 mg/kg after the 2014/2015 season). To prevent an excessive ethyl ester production and preserve the highest fat quality in the processed olives (parameters comparable to those of EVOO), the activity of yeasts during fermentation should eventually be controlled (e.g. by the use of starter cultures of lactic acid bacteria or by the application of some yeast strains with reduced or non-ethanol producing ability).