Minor polar compounds of olive oil: Composition, factors of variability and bioactivity

The adoption of the Mediterranean style of diet is recommended for reducing the risk of developing chronic illness, mainly coronary heart disease and cancer. The Mediterranean diet reflects the food pattern of Greece, Southern Italy and Crete in the early sixties and is characterized by high consumption of plant food (fruits, vegetables, breads, cereals, potatoes, beans, nuts and seeds), moderate consumption of fish, poultry and dairy products, low amounts of red meat and low to moderate intake of wine. Olive oil is the dietary fat of choice in Mediterranean countries, but its consumption is increasing elsewhere in USA, Japan, Russia and Canada. Olive oil has a peculiar fatty acid composition rich in oleic acid (56-84% of the total fatty acids) and linoleic acid (3-21%). In addition it contains a variety of minor constituents responsible for the unique organolectic properties and stability to oxidation. Unsaponifiable fraction of olive oil is of a diverse chemical nature. The composition varies depending on cultivars, drupe ripening, climate and enviroment, time of harvesting and storage and processing techniques for the oil production. The highest concentration of these compounds is in the extra-virgin olive oil, obtained by the first cold pressing of the olive paste. The minor components are important not only from a commercial standpoint in order to assess the high quality and good palatability of the oliveoil, for but also for their potential beneficial impact on human health. As concerns the nutritional aspects, the antioxidant and free radical scavenger properties of the phenolic portion of the unsaponifiable fraction were seen as highly relevant. The most recent research reports on a variety of biological activities demostrated in in vitro studies (protection of low density lipoproteins from oxidation, inhibition of platelet aggregation and production of pro-inflammatory mediators etc.). Indirect evidence that olive oil phenols might act also in vivo should stimulate future research for measuring bioavailability and kinetics following dietary intake and confirming in vivo reproducibility of in vitro data.