Part of our weekly "In Focus" series—stepping back, looking closer.

The farm-to-table trend is cooking. Urban gardening is on the rise. And high-end chefs are riding the locavore wave, promising superior, sustainable ingredients that can be traced back to their fields and pastures, which are often just a few miles down the road.

It feels as though a new age of food transparency has dawned.

But has it really?

As shown by Europe's recent horsemeat scandal—in which scores of products labeled as "beef" were found to contain up to 100 percent horsemeat—and arrests last spring of Chinese traders who were allegedly peddling rat meat as lamb, there's still considerable mystery around where a lot of our food comes from.

In many cases, that mystery extends to exactly what it is we're eating.

"Unfortunately, controlling the amount of fraud that occurs daily in the food industry is next to impossible," said Michael Roberts, a professor of food law and policy at UCLA and director of the Center for Food Law and Policy.

"Almost anything can be adulterated in some way," he added, "either to persuade consumers to buy something for their health, or by diluting it to save money on the supplier end."

It's a problem that spans the globe.