Comparison of olive oil (Olea europaea) quality extracted by stonemill and hammermill

This study compared two olive oil extraction processes used in New Zealand to assess the influence of processing on oil quality. The extraction systems included an Enorossi stonemill and an Oliomio 50 hammermill, malaxing basin, and centrifuge. Olives (Olea europaea) from individual harvests were found to show significantly higher polyphenol and chlorophyll content from the hammermill process. Slightly higher free fatty acids resulted from the hammermill. Fatty acid profiles did not show significant differences between the methods of extraction. Storage over 17 months resulted in increased peroxide values for both oils but no change in chlorophyll, free fatty acids, or polyphenols.