What about the other “extra virgin” vegetable oils?
- The term ‘extra virgin’ means not only that olive oil was extracted by mechanical means (no thermal treatment, no solvents), but also that the oil has passed a chemical analysis (free fatty acids, peroxides, UV absorbance and now, in California and Australia, two new methods to detect oxidation/rancidity/adulteration), the parameters of which are meant for olive oil only.
- The latter also applies for the question of ‘cold press’ status, which some vegetable oils claim as a basis for their self-proclaimed ‘extra virgin’ condition. ‘Cold press’ does not mean EVOO. It is an old term, originating from the time when olive oil was extracted via stone mills, a system that has been abandoned due to its high oxidative aspects. It’s true that EVOO must be made with lower temperatures (under 28C/ 82F), though that does not mean that all oils made under that parameter will be automatically EVOO.
- Very importantly (since this establishes the difference between extra virgin and virgin), it also means that the olive oil in question is free from organoleptic defects. No rancidity, fermentations (fusty, winey) or other noticeable defects are allowed for the grade EV.
- Olive oil is the only vegetable fat that has a significant endowment of natural anti-oxidants (polyphenols and tocopherols). This unique characteristic is the main factor that sets it apart, making EVOO the only fat subject to sensory evaluation regulated by law. The other vegetable oils don’t have a significant presence of anti-oxidants, if any at all.
- The other important difference occurs in the fatty acids composition. Oleic acid (55-85% in olive oil) has a great stability compared to other acids, which predominate in most vegetable oils. The higher presence of linoleic and linolenic acids make the latter highly unstable. In fact, that’s why these oils can’t be subject to sensory evaluation: they become rancid from the early stages of their lives. The lack of polyphenols subjects these oils to inevitable and rapid oxidative decay. This is so important that it also applies to olive cultivars: some are more stable or unstable given their genetic make up in terms of fatty acids and polyphenol count. For instance, Arbequina or Arbosana olives are much more unstable and prone to an early deterioration than Mission or Tuscan varieties.
Some vegetable oils made with better extractive technologies have had a formidable marketing victory, generally thanks to the supposed benefits of Omegas fatty acid 3 & 6 in oil form. This would be another discussion subject entirely, since as we understand, they are much better sources for these, when presented in any balanced diet.