Quality assessment of refined olive oils by gas extraction

Olive oil is a vegetable oil that is extracted from olives by mechanical means. Fractions of the oil thus produced have a high content of free fatty acids and require refining. Conventional refining processes may, however, alter the nutritional qualities of the oil. In recent years, a study was carried out to evaluate the feasibility of deacidifying olive oil by supercritical carbon dioxide extraction. Extensive deacidification, resulting in low acid contents of the raffinates, was obtained. Results obtained for other quality aspects of the supercritical fluid refined oil are reported here. Raffinates were analysed to determine their overall ultraviolet absorbance, triglyceride profile by high-performance liquid chromatography and stigmasta-3,5-diene content by gas-liquid chromatography. The analyses made have shown that extraction with supercritical fluid did not alter the nutritional quality of the processed virgin olive oil.