Extraction of olive oil with supercritical carbon dioxide

Abstract

The principal objective of this study was to extract olive oil from the fruit of Olea europaea by means of supercritical carbon dioxide (sc-C02) as an alternative to traditional methods. Extractions were performed on a laboratory scale supercritical fluid extractor of the latest design, featuring three mutually independent flow systems and extremely high flow rates. A number of extraction runs based on a statistical design was performed to establish the conditions (time, pressure, temperature) for a maximum yield of extracted olive oil. These conditions turned out to be 50 OC and 460 atm (corresponding density of 0.953 g/mL) for a 60 minute extraction run. The influence of different variables on the yield of extracted oil was investigated by means of computer-assisted surface response analysis. Additional extraction runs were performed at selected conditions to make reliable conclusions regarding the temperature, pressure and density dependencies of the extraction process and the nature of the mechanism of extraction. The density of the extracting fluid was found to be the key variable which limits the extraction by the extent to which olive oil dissolves in sc-CO2. The composition of the sc-C02 derived oil was determined by GC-GCTTOF-MS analysis and compared to that of commercial olive oil. A total of 27 peaks were detected in the chromatogram of the sc-C02 derived oil as opposed to 37 peaks observed for commercial olive oil. These peaks could all be identified, and the two major components in the sc-C02 derived olive oil are hexadecanoic and oleic acid. The quality and composition of the oil were evaluated against standard specifications of the International Olive Oil Council and classified on the basis of these criteria as lampante olive oil. This oil is suitable for industrial use but not for human consumption.