You may have heard by now that the olive oil in your kitchen cupboard may be an impostor. After a 2010 report found that 69 percent of imported olive oil in the U.S. failed to meet international standards, thousands of news stories were published, often incorrectly describing the presence of “fake” olive oils in grocery stores. Shoppers everywhere have been terrorized since, afraid that the olive oils on aisle nine may as well be Louis Vuitton bags from New York City’s Canal Street. 
 
 The hysteria recently led Congress to assign a new job to the the Food and Drug Administration: sampling imported olive oil to see whether it’s adulterated or fraudulently labeled. That testing and any new regulations that result will probably go a long way in filtering out low-quality oils from grocery shelves. But there’s something that not even the mighty FDA can fix: most of us don’t know the difference between a high- and low-quality olive oil. 
 
 Though there’s a long history of scandal in the olive oil world, the problem in the U.S. for consumers is less about oil that isn’t made from olives, and more about olive oil that doesn’t meet the quality standards declared on its label. But since most people in the U.S. can’t tell fusty and musty from pungent and fruity, low-quality olive oil masquerading as extra virgin is a hard problem to fix. 
 
 “We call the U.S. the world’s dumping ground for rancid and defective olive oil. We don’t know the difference,” said Sue Langstaff, a sensory scientist who consults for the beer, wine and olive oil industries, among others. Studies have shown that even frequent olive oil consumers in the U.S. don’t know what the extra virgin or cold pressed designations mean, let alone have the ability to taste the difference. And in blind taste tests, consumers often prefer lower-quality olive oils. 
 
 Rancidity, for example, isn’t generally a sought after quality in edible products. And yet, when it comes to olive oil in the U.S., people like it. Why? Partly, because rancid olive oil is less bitter than the good stuff. But also, likely because it’s what many of us know and grew up with. It’s what we think olive oil is supposed to taste like. 
 
 There’s nothing inherently wrong with liking rancid olive oil. There is, however, a problem with thinking you’re buying extra virgin and getting low-quality oil instead. For starters, because extra virgin oil is harder to make, it commands higher prices. There are also potential health benefits associated with extra virgin oil that aren’t necessarily present in lower-quality versions. 
 
 The money involved has long left the olive oil industry vulnerable to fraud. In 1959, the United Nations started a council, now called the International Olive Council, which was tasked with dealing with olive oil fraud. After decades of experimentation, the IOC came up with a method of tasting that has been used by law in Europe since the 1980s with few changes. It dictates the role of both lab instruments and humans in determining what can be labeled extra virgin olive oil. As Langstaff wrote, “With this law, olive oil became the first food in the world whose quality was legally determined at least in part by its sensory properties.” 
 
 What she meant is, the extra virgin classification is determined largely using humans as lab instruments — expert tasters trained to perceive 16 defects in olive oil. The presence of defects disqualifies an oil from being classified as extra virgin, though there’s not necessarily something inherently wrong with how the defects taste or smell. Instead, each one is associated with a flaw in the production process. Storage temperatures, exposure to light or oxygen, harvesting methods, the amount of time from harvest to crush, the cleanliness of equipment … each aspect of production can change the chemistry of the oil or produce flavor attributes considered undesirable if it isn’t carefully executed. 
 
 When olive oil is oxidized, frequently via light exposure or storage problems, peroxide is formed. When those peroxides decompose, the olive oil gets rancid. Fusty olive oil is created when olives begin to ferment in the absence of oxygen while in storage. More polyphenols generally means more bitter, pungent oil, which is considered positive. 
 
 There are some fairly blunt machine tests that can be performed, but ultimately it’s up to humans to determine the quality of olive oil. With training, the mouth and nose go from being a dipstick, which crudely measures good and bad, to a sensitive instrument, capable of discerning small variations in taste and aroma. For an oil to get the designation of extra virgin, it must receive a median score of zero for each defect or an oil will fall from grace, declining in the ranks from “extra” to simply “virgin.” (Fall too far down in these categories, and the olive oil is designated “lampante,” or lamp oil, which is “unfit for human consumption.”) 
 
 But Langstaff, who leads a professional olive oil tasting panel, points out this is not how we do things at home. “You’re a human gas chromatograph. You don’t ask if you like the olive oil, you’re just a machine,” she said. Most people lack the language to differentiate their preference for various oils. Unlike with sight and sound, we spend very little time learning about or describing what we taste and smell, which leaves many unable to state their preferences. 
 
 But what if we could learn how to better articulate what we like? Consumer research on olive oil preferences is often conducted through a method called descriptive analysis, where the first step involves helping people establish a lexicon for the flavors they perceive. That facilitates data collection, but also gives tasters the tools to refine how they taste. 
 
 That’s because having language to describe an experience likely changes the experience itself. We know that language helps us differentiate colors. Light, after all, exists on a spectrum; in many cultures there was no differentiation in language or perception of blue and green until the modern era. And among social scientists, there’s relative agreement that language influences our thoughts and experiences, though there’s debate over the degree of that influence. 
 
 Perhaps, then, placing a greater emphasis on learning how to describe what we eat could increase the joy we get from consuming it. It’s difficult to come up with a surefire way to train our palates at home since grocery store offerings can be unreliable. Still, I found a fairly simple experiment useful in beginning to learn the language of olive oil, and the flavors that go with it. Buy a California brand olive oil at the grocery store, one that’s certified by the California Olive Oil Council. Then buy a bottle labeled just virgin to compare. Try a sip of each of them solo, to get a sense of their flavors. Since most of us aren’t in the habit of drinking olive oil, the real taste testing comes from then trying the oils on toast, and using them in a cooked dish. Do this with a friend or a notebook, so you can talk about what you’re tasting. For most of us, the first step to experiencing great olive oil is probably learning the language that defines it, and the flavor of those descriptors. 
 
 This was an edition of The Digest, a FiveThirtyEight column exploring the science, history and economics of food. We’re still working out the essential ingredients to make this just right — we welcome your feedback and suggestions! You can email me, leave a note in the comments, or find me on Twitter. ||||| Tests have found that many olive oils claiming to be extra virgin are, in fact, not. And consumers are getting ripped off, shelling out big bucks for what they think is pure olive oil only to end up with a product containing soybean and other cheaper oils. With so much olive oil fraud happening, there's a chance you've been spending a little extra money to make sure you're getting the real deal. 
 
 Extra virgin olive oil is frequently more expensive than the non-extra virgin variety, and very good quality EVOO can get pricey. However, quality EVOO can also go rancid more quickly than other oils. 
 
 What does rancid mean? 
 
 Foods that have fats or oils in them can go rancid, or stale. Foods that have gone rancid have a "rank smell or taste usually due to chemical change or decomposition," according to Vocabulary.com. 
 
 EVOO comes from the first press of olives. When the olives are pressed, the oil is extracted naturally, using no heat or chemicals. It's basically olive juice, and to be labeled extra virgin, it must have no defects. Once this high quality oil spoils, not only will it taste and smell bad, its health benefits will be diminished also. The antioxidant polyphenols in the oil, the same compounds that make red wine healthy, will have disappeared, the Daily Meal reports. 
 
 How to detect a rancid oil 
 
 If you're not sure if your extra virgin olive oil is still good, a big sniff is the first step in finding out. (Photo: lithian/Shutterstock) 
 
 I bought my first really good, expensive EVOO at a wine expo about a decade ago. I spent $25 on a small metal container of oil from Italy. I brought it home, used it once, put it in the cupboard above my stove, and forgot about it. Eventually, it got shoved to the back of the cabinet, and it wasn't until about five years later that I rediscovered the container way out of sight in the high cabinet. 
 
 When I opened it, there was no doubt the oil had gone rancid. The smell was enough to convince me to toss the entire container. What a waste. 
 
 Rancidity is not always that obvious, and it can happen long before the oil is five years old. The Daily Meal suggests the following steps to test for rancidity using both your sense of smell and taste. 
 
 Pour a small amount of olive oil into a cup so you can get a good sniff. If the oil has an unpleasant sweetness, "like fermenting fruit or fruit that's just gone completely bad," it's rancid. The sweetness is also described as being reminiscent of the smell of Elmer's Glue. Do a taste test, also, because many EVOOs have a naturally sweet smell that an inexperienced person could easily mistake as rancidity. Before tasting, warm the cup in your hands to bring it to room temperature. Slurp about a "tablespoon of oil into your mouth without swallowing or exhaling, keep slurping, breathe out, and if it's completely tasteless, it's rancid." 
 
 If your EVOO, or any other oil, has gone rancid, there is no saving it. 
 
 How to keeping EVOO from going rancid 
 
 The good news is there are ways to prevent extra virgin olive oil, and other oils, from going rancid, or at least slow down the process. ||||| Getty Images 
 
 We have an oil problem on our hands, and it has nothing to do with renewable energy and carbon emissions. 
 
 When experts convened recently at the 104th annual meeting of the American Oil Chemists’ Society, there was heated debate over what to do about olive oil. Even though concerns over poor quality, mislabeling and outright fraud surfaced a few years ago, olive oil continues to be plagued with credibility issues, even as it finds its way into more American homes and countries around the globe attempt to set quality-control standards. The state of extra-virgin olive oil — which is extracted from olives via mechanical means, not chemicals or heat — has been particularly controversial. While some industry insiders insist that stories of rampant adulteration are greatly exaggerated, others beg to differ. 
 
 (MORE: It’s the Olive Oil: Mediterranean Diet Lowers Risk of Heart Attack and Stroke, Study Finds) 
 
 Among the conference participants was Dan Flynn, executive director of the Olive Center at the University of California at Davis, who a few years earlier had assessed the quality of extra-virgin olive oils in supermarkets based on standards set (but not enforced) by the U.N.-chartered International Olive Council as well as two additional chemical criteria. Shockingly, he found that 69% of imported olive-oil samples and 10% of California samples failed to meet sensory standards such as having more than zero fruitiness and not being rancid. Thirty-one percent were also deemed oxidized or of poor chemical quality. This year, Flynn followed up with more bad news. Among 15 samples of extra-virgin olive oil from restaurant suppliers, one was adulterated with canola oil, and a whopping 60% failed to reach sensory and chemical standards defined by the term extra-virgin. 
 
 Last spring, in the hope of improving matters, the USDA invited olive-oil brands to comply voluntarily with its Quality Monitoring Program. But so far only one company — Pompeian, the second largest olive-oil bottler in the U.S. — has chosen to participate. To do so, Pompeian officials say, they have had to greatly increase the size of their quality-control department, spending “several hundred thousand dollars” for staffing, training, research and record keeping. 
 
 Some industry groups argue that monitoring simply isn’t feasible. The vast majority of olive-oil brands in supermarkets come from companies that don’t own a single olive tree. They obtain the oil from middlemen, who don’t necessarily get it directly from the grower (or, in most cases, growers). With so many hands in the vat, it’s tough to know when and where adulteration or spoilage occurs unless there’s an inspection at every step of the way. And let’s not forget about the shippers and retailers involved before that bottle ends up in your pantry — even the best oils will deteriorate if left in a hot truck or near a sunny window. 
 
 (MORE: The Forgotten Benefits of Chinese Food) 
 
 Then there is the problem that there are several certification programs besides the USDA’s and that test results can vary even when similar standards are used. Quality can change from year to year, from sample to sample. For example, even though Bertolli and 365 100% Italian both earned quality seals from the North American Olive Oil Association (NAOOA) and Pompeian earned USDA and NAOOA seals, 33% of the 45 samples tested from the three brands failed to meet chemical standards and 84% failed to meet sensory standards when assessed two years ago by UC Davis’ Olive Center. In another study performed a year later, the results for Pompeian and Bertolli were still not 100%, so competitors have questioned whether these products actually improved. But Eryn Balch of the NAOOA argues that taste can be subjective, changes over time and in this case has “nothing to do with adulteration.” She also claims that the reports out of UC Davis are funded by California olive-oil companies and that the panelists were partial to promoting domestic oils. 
 
 Flynn responds that the criticisms of the panelists are irrelevant, since they are professionally trained, and that fustiness and mustiness do not result from mishandling in shipping or storage but reflect the quality of the olives. Meanwhile, the California Olive Oil Council, which has its own seal program and requires local brands to participate, reports that the imported olive oils that it samples randomly from store shelves “come in at about 75% not extra-virgin grade.” 
 
 While we’re waiting (and waiting) for the various factions to stop pointing fingers and start working for the good of olive oil as a whole, remember this: as long as we keep thinking of olive oil as a shelf-stable condiment instead of the perishable product it is, someone might try to dupe us somewhere along the supply line — and we might not even know the difference. Fossil fuels may be more finite, but olive oil still has an expiration date.
– 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.)