Tracking Down Fraud

Food safety is a yes-or-no proposition — either there is a contaminant or there isn’t. Food fraud, a smaller segment of the universe of problem foods, is harder to detect because it can take so many forms. Fish from a country whose imports have been banned might arrive at the market labeled with a different country of origin, honey might be cut with cheaper extenders, and saffron might not even be saffron.

When asked if fake food has ever crossed the threshold at Costco, Mr. Wilson smiles and says, “I’m going to go with ‘no,’ but you’re not going to believe me entirely. Yes, there have been egregious things, and we’ve taken care of them, and that’s that.”

Olive oil is a popular target for fraud because there are several ways to charge more for less. Compliance with United States Department of Agriculture quality standards for extra-virgin olive oil is voluntary. Unless a supplier pays for testing, passes and puts a U.S.D.A.-certified sticker on the bottle, consumers have no way to know whether they got extra-virgin olive oil. Any grade of olive oil can be doctored with cheap filler oils like canola, because they have no flavor. And the country of origin listed on the label isn’t always where the contents are from.

About five years ago, Mr. Wilson decided it was time to send an employee to Tuscany to collect leaves from Tuscan olive trees. Costco now has an index of DNA information on “all the cultivars of Tuscan olive oil, about 16 different ones,” he says. “When they harvest and press, we do our DNA testing.”

A group of undergraduates at the University of California, Davis, has developed the OliView, a biosensor that can detect rancid or adulterated olive oil. They expect to have the device ready for sale, at $60 to $80, in 18 months to two years. “At the supermarket level, we found that a lot of times the oil was just old and rancid,” says Selina Wang, research director at the U.C. Davis Olive Center and one of the students’ advisers, “but there were also samples labeled extra virgin that were actually a little bit of virgin olive oil mixed with refined olive oil.”

Adulterated oil, more common among imports, can stump even food professionals. Ms. Wang says that at the center, they “have seen samples with as much as 70 percent canola oil.”

DNATrek has also developed a test for products where fraud is a temptation — “high-value stuff, truffles, saffron, premium juices, honey, seafood and olive oil,” Mr. Zografos says.