As long as you maintain at least 160 degrees, steeping will pasteurize the fruit so you don't get any weird **** in your beer. I used frozen raspberries, and the steeping also broke them down some so I wasn't dumping un-thawed berries in my beer. 20 minutes will give you a mice raspberry mush that will break down nice in your beer. You might consider straining it before bottling, but I didn't and it seemed to be fine. The beer is a little pulpy but nothing a good pour doesn't fix.