Cacao bean types are sometimes mixed up during the harvesting process, so a manufacturer might think they're getting a high-quality bean, but until now there was no way to tell. The new method screens beans based on their DNA and can match the beans to their corresponding tree.

The ability to authenticate premium and rare varieties of cacao means buyers will know which product they're paying for.

Lyndel W. Meinhardt, Ph.D., a USDA scientist familiar with the research, said that there are about 13 or 14 different types of cacao beans.

“This only really affects the premium types because [manufacturers] get more from it,” Meinhardt said. “We’re actually adding another level of authentication on top of the sole source. It’s kind of taking your premium chocolates into the next realm.”

You can discern healthier chocolate based on its cacao content. The greater the percentage of cacao, the darker the chocolate, and the more heart healthy flavonoids it contains. 

Andy Bellatti, a nutritionist from Las Vegas, said cacao (and cocoa, once it’s processed) is a healthy food—but certain types are better for you than others. The three main fats in cocoa butter are oleic acid, the same heart-healthy monounsaturated fat found in olive oil; stearic acid, a saturated fat the body converts to oleic acid; and palmitic acid, which has been shown to slightly increase "good" HDL cholesterol.

Dark chocolate is rich in antioxidants, fiber, magnesium, and copper as well.

“You need to know how to find [chocolate] in ways that are minimally processed so you get the most nutritional bang for your buck,” Bellatti said. He advises picking a chocolate with the fewest number of added ingredients.

It may be good for you, but don't pig out.

"Portion control cannot be stressed enough," said Jaclyn London, senior clinical dietitian at The Mount Sinai Hospital. "Just don't exceed the one-ounce portion."

Here are a few guidelines for choosing chocolate that melts your heart.

“The higher the cocoa content of a chocolate bar, the higher the flavonoid content and, more importantly, the lower the sugar content,” Bellatti said. Make sure cocoa appears before sugar on the label’s list of ingredients.

Products with a cocoa percentage over 70 percent are considered dairy-freesomething else that’s good to know.

“Cocoa beans have some of the highest pesticide loads of any crop,” Bellatti said. Due to weak regulations in countries that produce cacao beans, pesticides banned in the U.S. are still used in conventional cocoa farming.

“It’s not that alkalized chocolate is ‘bad’ for you, but rather that the processing significantly decreases the amount of healthful antioxidants and flavonoids that you get in unprocessed cocoa,” Bellatti said, adding that some of the most processed cocoa products contain alkalized cocoa.