Extra-virgin olive oil is a wonderful thing. The "extra virgin" designation indicates the highest quality: Olive oil extracted from the first pressing that has an acid content of less than .8 percent.
Organic extra-virgin olive oil is the only oil on the Spartan Diet. But there's a problem. A recent study by the University of California at Davis Olive Oil Center, in collaboration with the Australian Oils Research Laboratory, found that many products labeled as "extra virgin olive oil" in fact are not.
Unlike in Europe, where the "extra-virgin" designation is defined by law, there is no enforcement of standards in the United States.
Researchers found that 69 percent of imported oil labeled as "extra-virgin" in fact was not, whereas 10 percent of oils produced in California and sold as "extra virgin" were not. However, nearly all (99%) of oil labeled as extra-virgin olive oil in the United States is imported, so many American olive-oil eaters have never even tried US-made olive oil.
Researchers found that a wide variety of events can disqualify olive oil from the extra-virgin designation. Inferior-quality olives, oxidation of the oil, improper storage or the addition of lower-quality oil all can ruin olive oil and make it not truly extra virgin at the time of purchase.
In other words, many olive oils sold as extra virgin in fact did qualify at the time the oil was pressed, but has been degraded by some event later in the storage, transportation or bottling process. Oil can be oxidized, for example, by sunlight, heat or oxygen. The oxidation process raises the acidity level to above the "extra-virgin" limit, no matter what the label says.
This may explain why California olive oils tested so much better than imported oils: UC Davis is in California, so the California oil was all local, less handled and probably fresher.
Even olive oil that's high-quality extra-virgin stuff when you buy it can degrade in your kitchen. Improper storage (with sunlight or heat) can damage the oil, of course. But even in ideal conditions, the quality of olive oil naturally degrades over time. One study found that after 6 months, olive oil loses about 40% of its antioxidants.
You can also ruin olive oil at the last minute by cooking it at too high a temperature.
So what's an olive-oil obsessed Spartan Dieter to do? First of all, we need to think of extra virgin olive oil as something different than the indestructible cooking oils we grew up with. Because it's unheated and unprocessed, olive oil is really almost a fruit juice.
You want to make sure your extra-virgin olive oil comes from a reputable producer, has been properly stored and handled between the producer and the store, and has been pressed as recently as possible.
Some farmer's markets offer locally produced extra virgin olive oil. Because you're buying it directly from the producer, it's less likely to have been damaged during shipping and so on. This is not always the case, however. Grill the seller until you're satisfied he or she is doing it right and selling the real deal.
Look for domestic olive oil, wherever you live. The less transportation the oil undergoes, the fewer the opportunities for spoilage.
Buy only organic. In our experience, organic producers tend to be more honest and more careful with oil quality. Besides, who wants pesticides in their salad?
Look for acidity level. Some olive oils proudly boast of their low acidity levels. This is a good sign. The lower, the better.
Ultimately, however, there is no substitute for becoming an olive-oil snob and knowing the difference based on how oil looks, smells and tastes. Because even good oil can go bad in your kitchen.
Look for olive oil tasking opportunities, and cultivate your ability to tell good oil from bad, virgin from non-virgin and extra from not-so-extra.
Extra-virgin olive oil in small quantities is the foundation of the Spartan Diet. But if you want truly extra-virgin olive oil, you can't just passively accept what labels are telling you. You've got to fight for high-quality olive oil -- but it's worth the battle.
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