Here’s What Makes Potency Testing of Cannabis Edibles Difficult

Approximately five years ago, Canadian cannabis edibles pioneer Brandon Wright ran up against a testing problem. He was producing cannabis brownies following a 2015 decision by the Supreme Court of Canada that guaranteed licensed medical patients the right to produce and possess edible cannabis products, and he wanted patients to be certain that each brownie he served contained the same very high dose of 200 mg of cannabinoid tetrahydrocannabinol (THC).

Yet, despite sending three brownies per batch for testing, his labs reported wildly different results, which confounded Wright. “I later found out they were breaking off a corner of each brownie, [reducing it to powder], and testing that,” Wright says. The problem, he eventually figured out, was “hot spots,” which may be acute in non-homogenous cannabinoid products such as brownies. Wright warns that the lack of homogeneity within a food product containing 200 mg THC means that the end product “is likely going to have micro-hot spots, even with a production process that is excellent at mixing and homogenizing.”

Cannabinoids are fat soluble and likely to cluster in small deposits within a baked good rather than being uniformly distributed, so even in an extremely potent product (200 mg is 20 times the 10 mg-per-serving limit imposed by some U.S. states), one part of such a food item may contain more or less THC than another.

Because of hot spots, a brownie containing 200 mg of THC has the cannabinoid distributed only somewhat uniformly. To get the readings Wright was looking for, his lab needed to reduce each complete brownie to homogenous powder and sample from that powder. “I could then analyze those results to determine the milligrams of THC per gram of brownie and adjust production processes accordingly,” he says.

What Makes Potency Testing of Edibles Difficult

For food and beverage producers who pivot into cannabis-infused products, traditional food-safety testing practices remain essentially the same. Yet producers of cannabis edibles and beverages face an important test particular to their industry: potency. Potency is generally measured in milligrams of active cannabinoids, such is the best-known THC (responsible for cannabis’s psychoactive effects), the popular non-impairing cannabinoid CBD, and other less-understood cannabinoids such as cannabigerol (CBG), cannabinol (CBN), and cannabichromene (CBC).

Mike Hennesy, director of innovation for Colorado edibles producer Wana Brands, notes that, in its plant form, cannabis is a very pharmacologically diverse. “You have cannabinoids; you have terpenes. Some growers have used pesticides, and it also soaks up things like heavy metals and microbials. No one piece of equipment is perfect for [testing for] any one of them,” he says. And, that’s just for testing cannabis flower. Depending on your product, testing food items for cannabinoid potency runs from complicated to extremely complicated.

For Amber Wise, PhD, the scientific director at Seattle’s Medicine Creek Analytics, the next question is this: homogenous or non-homogenous? “A gummy is really homogeneous. It’s well mixed,” Dr. Wise says. “But a chocolate chip cookie, for instance, is not.” As infused-food producers try to concoct a winning combination of cannabinoid dose and flavor profile, her lab has received a wide variety of food products to test. “We’ve received jalapeño ranch-flavored pretzels [and] caramel popcorn.”

With complex foods featuring multiple ingredients, Dr. Wise encourages producers to submit a significant number of the items for individual testing. “If you’re making cookies or brownies, sending in 20 of those and paying for 20 individual tests, [you can] see the spread of the lab you’re using,” she says. “That gives you a better idea of, if I send in any random cookie, are they going to give me a number that is a narrow range? It gives you a sense for the spread of your product and that lab together.”

The Power of Test Prep

Hennesy says that the way a lab conducts preparation for potency testing will determine the accuracy of the results. “Test prep cannot be underestimated as one of the most important variables from lab to lab,” he adds, noting that ingredient differences among products must be reflected in how labs prepare their samples for testing, or the results may be corrupted.