How Fats May Interfere with Potency Testing in Cannabis-Infused Chocolate

In addition to dried cannabis flower and infused foods and beverages, clients of Dr. Wise’s lab have also brought her topical products for testing. Sometimes, the contents may be very simple, such as only coconut oil and added cannabinoids. Clients, accordingly, often figure that if the mixture is simple, the science behind it must be as well.

Not so, says Dr. Wise. “It’s actually really hard to get a number out of [cannabinoids dissolved in fats],” she adds. “People don’t understand the fundamental solubility issues occurring here. Most everyday people are only familiar with water-based chemistry.”

Dr. Dawson is familiar with fat solubility, so the outcomes he discovered weren’t a total surprise. After all, he says, “chocolate is a very, very complex food matrix.” Considering cocoa solids alone, milk chocolate contains roughly 50 different types, while dark chocolate contains roughly 70. “Those cocoa solids are 50 or 70 unique, identified organic molecules that contribute to the nuanced chocolate flavor,” he says. “On top of that, there are the fats—cocoa butter, say, or milk fats added to milk chocolate. Fats are chemically distinct from the organic flavor molecules. Additionally, we have the sugars added to chocolate. The organic flavors, the sugar, and the fat are three very broad, wide-ranging chemical classes. It is a very complex matrix.”

Helene Hopfer, PhD, the Rasmussen Career Development Professor in Food Science at Penn State’s Department of Food Science in University Park, Penn., concurs. “Chocolate, if you look at it, about 50% is fat—cocoa butter—[and] the other 50% is cocoa solid: starch, polyphenols, proteins. That changes during processing, during roasting. In order to get chocolate, you need to go through that roasting step to create those flavor compounds. It’s a complex food like a lot of other complex foods: Think of wine, distilled spirits, or tea.”

The chocolate products Dr. Dawson tested were 42% fat by weight, and cannabinoids are fervently lipophilic. “Obviously, the cannabinoids are going to have some kind of desire to remain in the matrix,” he says. “They’re having positive chemical reactions with the fats in the chocolate matrix. That’s something that needs to be overcome [in order to get a clear read on cannabinoid contents].”

Some clients have been adamant with Dr. Wise that if they added 10 mg THC per serving of their product and don’t see test results showing 10 mg, it’s a lab error. She disagrees: “It’s not my math that’s wrong. It could be your mixing, or a thousand other molecules in this mixture that are interfering with our signal as a lab. I’m happy to explore it more deeply, but that costs time and money.”

The bad news is that this issue isn’t just about chocolate but impacts any infused product with a high fat content. Dr. Dawson warns that this reaction could occur easily in any baked good, such as brownies. “Anything that’s thick and rich and creamy could very well display an analogous phenomenon,” he adds.

Dr. Hopfer agrees. “This is not a problem unique to chocolate. It will be similar with butter, probably.”

Where to Go from Here

Dr. Wise says that the issue of fats in foods causing diminishing test numbers isn’t impossible to resolve—the products just require a little more work. She suggests that formulators send their labs a “blank” solution of the same food product without cannabinoids. “We can run the blank mixture on its own to see if there are any interfering peaks that might look like cannabinoids,” she says. “We can also add a known amount of cannabinoids and do our extraction to see if we can get back all the cannabinoids we put in. That’s not perfect. David Dawson has been working on his research for a couple of years now; this isn’t something you can figure out overnight. But, we have ways of helping clients make sure there aren’t compounds interfering directly with their signal, and to be sure we can extract cannabinoids out of that matrix.”