Stout + 4 lbs berries in secondary

[ChrisJPassarelli]

Hi all!
I'm about to brew a 1.086 stout, and I want to add some berries. I was thinking of putting a 4 lb bag of frozen mixed ones (raspberries, blackberries, etc) in when I rack it to secondary.
Any idea how the yeast will respond? Will they tear through that and add a bunch more alcohol to the final product? Since I'll likely be aging it for a good while, what kind of impact could that ultimately have?

Cheers.

 

[ChrisJPassarelli]

Maybe I should clarify -- basically, are these fermentable sugars for the most part, or will it instead manifest as additional sweetness and body?

 

[WVbrewer]

There are some fermentables in the berries, and the yeast will consume them, but it's not going to boost your alcohol a great deal. Off the top of my head with 4lbs your probably adding 1% or less to your abv. I generally let my primary hit final gravity, allow it to clear, then siphon to secondary with the berries. I don't like to leave it on the berries for more than 2 weeks or you risk extracting undesirable flavors form the seeds and pulp (tannins and vegetal flavors). That's been my experience, hope that helps. Dave