Yes, I used some cocoa powder in the rub I used on the brisket I smoked on Tuesday. (QView in the Beef forum...)
While there is no obvious chocolate flavor (not sure I'd like it if there was), the flavor is still really good. I think that the cocoa contributed some overall earthiness and richness to the flavor profile.
The rub "recipe" I used was actually a hybrid of three or four different rub recipes, subtracting and adding ingredients, and changing some of the quantities / ratios.
¼ cup cocoa powder
¼ cup very finely ground coffee
½ cup brown sugar
¼ cup fine sea salt
2 tbsp ground black pepper
1 tbsp ground Thai white pepper
2 tbsp sweet Hungarian paprika
1 tbsp smoked paprika
1 generous tbsp chipotle powder
2 tsp garlic powder
1 tsp cumin powder
- I will be cutting down the amount of coffee next time. Not because of the flavor, but because we've found that we have trouble sleeping after eating the brisket. The effect is very similar to eating a couple generous handfuls of chocolate-covered espresso beans. Nothing immediately noticeable, but before long you realize that you're not tired at all. The effect - for us - is quite pronounced and has a duration of a few hours.
- I would encourage anyone who decides to try this recipe to not follow it blindly. Be creative, take a risk, make it your own. Discovery is one of the great the joys of cooking, IMO.