Every grocery store in America stocks a wide and unexpectedly economical variety of imported olive oils, the most respected of which have labels that read “packed in Italy” and “extra-virgin.”

In the minds of many Americans, the idea of authenticity of olive oil imported from Italy is taken for granted. In reality, much of the Italian-imported olive oil imported is actually made from cheap oil that is shipped there from other countries, such as Morocco and Tunisia. Italian refineries then doctor the oil, label it as extra-virgin and export it to America, where it’s assumed  – correctly – that average consumers will never know what’s really coming out of the bottle.

“People think olive oil is olive oil. It couldn’t be further from the truth,” said Brett Murray, director of sales for Castillo de Pinar, who I spoke with on the phone after The New York Times first reported on olive oil fraud in 2014. The company is based in Spain, the number one producer of olive oil in the world.

60 Minutes ran a story last week called Agromafia, explaining the connection between the Mafia and Italian olive oil industry. It reported that the Mafia makes $16 billion a year off  doctoring olive oil. Tom Muller, a journalist and widely regarded  expert on the subject, said that 75 to 80 per cent of extra virgin olive oils sold in U.S. supermarkets are corrupt.

Olive oil is graded using a two-step process. First, the oil is sent to a laboratory to be tested for acidity and other qualities. If the test results are within a certain range, it qualifies as extra-virgin. The next step is a sensory test, where the smell, flavor and texture of the olive oil is evaluated through a taste test performed by a panel of experts.

To perform an olive oil taste test, the panel members sit in closed cubicles and are served blue shot-sized glasses, to hide the color. They sniff, tilt the cup and slurp the oil, aerating it into a mist in the back of the throat. What they seek is a clean taste, green and grassy and often bitter, with a slight buttery texture and peppery finish that his in the back of the throat. There are dozens of notes a pure olive oil can generate on the tastebuds, and it takes a trained palate to sniff them out.

While extra-virgin is practically an oxymoron, the term “cold-pressed” is somewhat outdated. Olives used to be pressed, much like apples are pressed for cider. The second press referred to a second extraction in which the olives are treated with steam or hot water to release more oil. Hence the industry standard term “first press” we see today. But with modern technology, olives are often pressed – for lack of a better term – by a centrifugal extraction method, a process that spins the olives at a high speed and uses gravity to filter the pulp from the oil.

According to Murray, many bottles of olive oil that come from Italy are composed of a significant majority of refined olive-pomace oil – a colorless, flavorless oil that is extracted from leftover olive pulp – with just enough true extra-virgin oil to fool a taste panel. Murray called the taste panel a flawed system, and said that the only way to prove that olive oil is adulterated is with a chemical test. But in Italy, labs aren’t required to be certified by a governing body, and consequently the test results are easy to fake. Once the oil is bottled, labeled and shipped to America, there’s no stopping it from being sold as extra-virgin.

A study performed by UC Davis in 2010 revealed that an overwhelming 69 percent of foreign olive oils labeled extra-virgin being sold on shelves in California did not meet the international and U.S smell and taste standards for that grade. Thirty-one percent of those oils also failed the lab chemical test. The results suggested that the offending oils were either oxidized, made from damaged olives, or adulterated with cheaper oils such as seed oils.

Karen Lee Henry of Texas Olive Ranch in Carrizo Springs, Texas, suggests that the best way for people to ensure they are getting quality oil is to buy domestic.

“U.S producers are much more authentic than what gets bottled in the ports of Italy and shipped over here labeled as extra-virgin olive oil,” said Henry.

California and Texas produce a lot of high-quality olive oil, and with no mafia middleman the product is virtually guaranteed to be more extra-virgin than the imported counterfeits.