Rule #1: don’t believe what you read on the interweb about how to decarb hemp. No, it’s not 170°F for 20 minutes.
Industrial hemp and cannabis must be decarboxylated if it’s to be eaten, taken orally, or used topically. If you’re making cannabutter, infused coconut oil, edibles like majoon, tinctures, or any prepartion that won’t be smoked, the hemp needs to be decarbed first.
The majority of what the plant makes is THC-A and CBD-A, the acid forms of these popular cannabinoids. Heating hemp converts the THC-A to THC and converts CBD-A to CBD. (Because raw cannabis contains primarily THC-A eating uncooked cannabis doesn’t get you intoxicated. Heat decarbs THC-A turning it into THC. That’s why smoking marijuana gets you high.
There’s a lot of confusion online about proper decarbing. The answer depends upon what you’re trying to do.
For maximum THC-A to THC conversion, heat at 245°F for 60 minutes.
For maximum CBD-A to CBD conversion, heat at 245°F for 90 minutes.
Put dry hemp in a glass Pyrex covered casserole dish. This keeps the terpenes and other volatiles from evaporating off. You want to preserve all of the terpenes because they’re an important component in addition to cannabinoids like CBD. Decarbing results in a 10% weight loss so 30 grams becomes 27 grams. When properly decarboxylated, the hemp will be darker, drier, and will crumble easily. Decarbing smells. Be forewarned and plan ahead. If your oven has a delayed start function try decarbing in the middle of the night.
Because decarboxylating evaporates some of the terpenes, terpenoids, and other aromatics, try adding raw cannabis to your final product. It’s much like using finishing hops when making beer. The raw cannabis adds valuable terpenes. The trade-off is additional THC-A and CBD-A but the upside is more terps.