Baby a bit constipated?

My baby is 6months old and he is having a bit of a hard time pooping. I gave him pureed prunes and they did the trick but he shudders every time i feed it to him, and he even tastes them when they are mixed with something else. so i tried the juice to see if there would be any different but the juice didn't seem to give him any relief. i was just wondering if there was an other fruit i could give him to help with the pooping