Influence of fruit ripening on 'Cornicabra' virgin olive oil quality - A study of four successive crop seasons

The aim of this work was to study the influence of the stage of fruit ripening on analytical parameters which determine oil quality during four successive crop seasons, in an attempt to establish an optimum harvesting time for 'Cornicabra' olives. The majority of the analytical parameters, i.e. peroxide value, UV absorption at 270 nm, pigments, sensory scores, oleic acid and total sterols, diminished during ripening, whereas free acidity, linoleic acid and Delta -5-avenasterol increased. Oil extraction yield, oxidative stability, natural antioxidants and campesterol showed more complex behaviour. On the basis of the evolution of the analytical parameters studied the best stage of maturity of 'Cornicabra' olive fruits for processing seems to be a ripeness index higher than 3.0 and lower than 4.0-4.5. Results indicated that probably less than 25% of commercial 'Cornicabra' virgin olive oils were extracted from olives harvested at an optimum ripeness index. It is therefore of crucial recommendation to the industry to bring forward harvesting to further improve the quality of the virgin olive oil produced. (C) 2001 Elsevier Science Ltd. All rights reserved.