Fruit extract at bottling: need help with carbonation

Hey all,

Last year I brewed a cherry wheat and added 2oz of cherry extract at bottling time (yeah, it's a bit much...). I also added the typical 5oz of priming sugar, not realizing that there were also sugars in the extract. What resulted was something that I'm surprised didn't create bottle bombs. If I open one at room temp, it will fizz half of the 22oz bottle away. Opened at chilled temps, it's much better on conservation of the beer, but I still have to let it sit open in the fridge for a few hours before it's down to "normal" carbonation.

My question is, if I were to add 1oz of blueberry extract into my blonde ale at bottling time, how much priming sugar should I also add to get a good carbonation? Nobody so far has been able to answer this.

Thanks in advance!

P.s., I'm also adding a large can of Oregon Blueberry Puree in the secondary...will that be sufficient to add a subtle blueberry flavor and aroma to the beer? Maybe I don't even need the extract...

I added 2oz of peach extract to a porter I did last year, along with the 5oz of priming sugar, and no ill effects. It also turned out to be one of my favorite beers to this day!