Influence of the type of olive-crusher used on the quality of extra virgin olive oils

An experimental investigation was carried out to evaluate the quality of virgin olive oils obtained when either a hammer-crusher or a disk-crusher were used for the olive paste preparation; the effect of the temperature rise caused by rapid olive crushing was also assessed. Oxidative degradation in the oils obtained from hammer-crushed olives was significantly higher than in those obtained from disk-crushed olives as shown by the levels of oxidised triacylglycerols and the results of the oven test. A significant inverse correlation (p <0.001) was found between the Rancimat induction time values and the amounts of oxidised triacylglycerols as determined by the high-performance size exclusion chromatography analysis of polar compounds. These findings suggested that polar compound analyses, just as routine analyses, may be used as a suitable analytical tool to effectively evaluate the quality of virgin olive oils.