Do extraction procedures affect olive oil quality and stabilility?

Quality and stability of olive oil extracted using discontinuous (pressing) or continuous (centrifuging) procedures were studied. Virgin olive oils ex tracted from two olive varieties were stored for 17 months. Analytical para meters of oil quality (acidity, peroxide value, polyphenol content, chlorop hyll amount, fatty acid composition and triacylglycerol molecular species) were followed at different time intervals. Our results showed that no diffe rences exist between the two types of tested mill, since the studied parame ters were unchanged or varied slightly in the same range during the time of oil conservation. Changes depend on olive varieties rather than extraction systems used. Moreover, oils produced by the continuous system contain com paratively higher levels of polyphenols, which may confer to them greater r esistance against oxidation for long-term storage.