Our Olive Oil Is Often Rancid, and We Don't Even Know It

As consumers, we pay a price for extra virgin olive oil—and not just literally. The oil is extracted naturally from the first press of the olives, as opposed to using heat or chemicals. It's basically olive juice, reports Mother Nature News, and it must have zero defects. But in this more delicate state, it is also highly perishable, with a shelf life of around two years that is dramatically shortened if exposed to light and heat (hence olive oil tins or darker glass). A few years ago, a researcher found a "shockingly" high 69% of imported extra virgin olive oil samples (and 10% of California's) flunked standards including, say, rancidity or having more than zero fruitiness, reports Time. Now that same researcher has more grim news: Among 15 extra virgin olive oils tested from restaurant suppliers, one contained cheap canola oil and 60% failed to meet standards to be accurately labeled extra virgin.

What's more, as up in arms as many sensory scientists have gotten about the pressing matter, most Americans tested cannot tell if an olive oil has gone rancid and don't know what extra virgin or cold pressed even mean, reports FiveThirtyEight. In blind taste tests, Americans tend to prefer the lower-quality olive oils—perhaps because we have become so accustomed to them, perhaps because fresh olive oils are actually more bitter. "We call the US the world’s dumping ground for rancid and defective olive oil," one sensory scientist says. "We don’t know the difference." So why care? As high quality oil spoils, its health benefits diminish, too. (See how heat changes the taste of cooking oils.)