Perhaps it's different with berries, but I made a mango-peach wit recently, where I added peaches to the unfiltered wort at the end of the boil. I strained them a few days later (since I didn't filter after the boil, there were still coriander seeds and orange peel in there, which imparts odd tannic aspects), then, for the final 10 or so days of the secondary, I steeped with more fresh peach slices, and also fresh mango slices. No sanitizing of the fruit, and so far, the beer is impeccable, save for some overcarbonation.