Rule #1: don’t believe what you read on the interweb about how to decarb cannabis. No, it’s not 170°F for 20 minutes.
Cannabis must be decarboxylated if it’s to be eaten, taken orally, or topically. If you’re making cannabutter, infused coconut oil, edibles like majoon, tinctures, or any prepartion that won’t be smoked, the cannabis needs to be decarbed first.
The plant itself makes THC-A and CBD-A, the acid forms of these popular cannabinoids. Heating cannabis converts the THC-A to THC and CBD-A to CBD. Because raw cannabis contains primarily THC-A eating raw cannabis doesn’t get you stoned. Heat decarbs THC-A turning it into THC. Smoking marijuana decarbs the THC and you get 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 cannabis in a glass Pyrex covered casserole dish. This keeps the terpenes and other volatiles from evaporating off, which results in less odor. Decarbing results in a 10% weight loss so 30 grams becomes 27 grams. When properly decarboxylated, the cannabis 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 the decarbed cannabis. It’s much like using finishing hops when making beer. The raw cannabis adds terpenes to your final product. The trade-off is additional THC-A and CBD-A but the upside is more terpenes.