Impact of cocoa power on OG

Does anyone know how much the addition of cocoa power impacts the OG of a beer?

I brewed Jamil's hazelnut chocolate porter which calls for 0.5 lb of cocoa powder and noticed that my gravity increased a lot from what measured pre boil vs in the fermenter. (I added the cocoa power at t=0 minutes).

thanks!

I'm a little confused here for two reasons:

1. Cocoa has no sugar in it. Did you use raw powder or a sweetened one?

2. Your gravity should increase between the pre-boil and pre-fermentation measurements. If you start with 6-7 gallons of wort with a certain amount of sugar in it and boil it for an hour to get 5 gallons, the sugar doesn't go anywhere, the volume just decreases and the concentration of sugars is higher. Example: A beer with a target OG of 1.054 should probably measure around 1.043 pre-boil (assuming a full-volume boil).

The gravity increased more than expected based on evaporation during boil so I was wondering if it was due to the cocoa power impacting the density of the beer.

I guess that it is possible the I screwed up the pre-boil gravity measurement, maybe the wort in the kettle wasn't mixed up well enough.

I still have some cocoa left so I think I will dissolve some in water and see what it does to the density.

Specific gravity is a measurement of the density of the liquid in question not sugar content. So anything that disolves in water will raise the OG, That's why we calculate ABV based on the difference between OG and FG. Those unfermentable substances will still be part of the FG unless they fall out of suspension and become part of the sediment.