On a recent seg­ment of his wildly suc­cess­ful day­time tele­vi­sion pro­gram, Dr. Oz warned his view­ers they are being duped into buy­ing fake extra vir­gin olive oil (EVOO). He said some experts claim that nearly 70 per­cent of EVOO sold is coun­ter­feit, and he urged every­one to check their olive oil with a test that he and his fam­ily use.

In the test, Dr. Oz puts a bot­tle of EVOO in the refrig­er­a­tor. If it freezes at a nor­mal refrig­er­a­tor tem­per­a­ture, ​“then you’re pretty sure it’s pure,” said Oz.

Some experts, how­ever, say that the so-called ​“Fridge Test” for olive oil authen­tic­ity is a long-stand­ing myth.

Dr. Oz was inves­ti­gat­ing super­mar­ket food fraud, includ­ing fake EVOO, in an episode that aired on February 11. He explained that peo­ple pay more for good olive oilfor its health ben­e­fits, but if the oil they pur­chase is not EVOO, then they are not get­ting the desired health gains.

A 2010 study con­ducted by the University of California Davis Olive Center reported that 69 per­cent of imported oil labeled as extra vir­gin olive oil did not meet the stan­dards for extra vir­gin.

Show guest Dan Flynn, direc­tor of the Olive Center, told the over 3 mil­lion view­ers that EVOO is the top grade of olive oil because it is nat­ural crushed olive juice; not altered by chem­i­cals, sol­vents or heat. In the UC Davis study, falsely labeled sam­ples pulled off gro­cery shelves were described by trained tasters as ​“musty, waste pond, baby diaper…the kind of things you don’t want to get near your salad,” Flynn said.

Shaun Kennedy, direc­tor of the National Center for Food Protection and Defense, also appeared on the Dr. Oz Show and explained that some pro­duc­ers pass off cheap oils, such as sun­flower, hazel­nut or indus­trial oil as extra vir­gin olive oil because they can make a big profit on it. ​“Some esti­mates say that the fake olive oil busi­ness is as prof­itable as the cocaine trade and it’s cer­tainly a lot eas­ier,” said Kennedy.

While Dr. Oz’s show brought needed aware­ness of olive oil qual­ity issues to con­sumers, experts say the ​“fridge test” will not help con­sumers con­clu­sively deter­mine if their pur­chase is real olive oil. Dr. Oz informed view­ers that the method is ​“not 100 per­cent fool­proof.”

The North American Olive Oil Association called the home test ​“com­pletely false and mis­lead­ing.” Almost any oil will solid­ify at cold tem­per­a­tures, depend­ing on its chem­i­cal com­pounds, and even within the EVOO cat­e­gory, fac­tors such as olive vari­ety and time of har­vest, will affect solid­i­fi­ca­tion.

Expert olive oil taster Richard Gawel said that the home test ​“is not a reli­able indi­ca­tor” of an oil’s EVOO authen­tic­ity. In his blog, Gawel explains why the myth may have come into being. EVOOs are largely made of monoun­sat­u­rated fats that coag­u­late at refrig­er­a­tor tem­per­a­tures while other oils tend to be made of polyun­sat­u­rated fats that can only solid­ify at much lower tem­per­a­tures — lower than reg­u­lar refrig­er­a­tors can reach.

The fridge test would work if EVOO were 100 per­cent monoun­sat­u­rated and other oils were 100 per­cent polyun­sat­u­rated, said Gawel, but oils usu­ally con­tain a com­bi­na­tion of fats. He cites peanut oil as an exam­ple say­ing that it has high monoun­sat­u­rated con­tent and will pass the fridge test.

Even an EVOO that has been adul­ter­ated with a bit of canola oil will solid­ify in the refrig­er­a­tor and pass the test, even though it is not pure EVOO, said Gawel.

Flynn told Olive Oil Times that the refrig­er­a­tor method is not com­pletely fool­proof. ​“While it is true that refined oils will not coag­u­late in the cold, it is also true that some olive oil vari­eties will not coag­u­late either.” In addi­tion, the test will not tell a con­sumer if the EVOO tastes good.

Eryn Balch, exec­u­tive vice pres­i­dent of the North American Olive Oil Association said that the widely-cir­cu­lated fridge test myth ​“illus­trates the great need for reli­able sources of olive oil edu­ca­tion.”

Flynn advised view­ers of the Dr. Oz show to check the har­vest date on the olive oil bot­tle, and buy one indi­cat­ing a har­vest within the last 15 months to improve the chances of get­ting a good qual­ity oil. He also rec­om­mended look­ing for qual­ity seals on the bot­tles, such as the one from the California Olive Oil Council, that cer­tify that the oil has passed chem­istry and sen­sory cri­te­ria. Flynn noted that UC Davis is work­ing on bet­ter meth­ods of detect­ing olive oil fraud.