The fruit purees that are made for brewing and winemaking come pre-sanatized in large cans. That's the easy way!
Wineries don't even wash their grapes before pressing. Don't worry too much about it especially if additions are post-fermemtation.
Note that wild yeast is no where near as big of a deal in winemaking as it is in beer.
If you use fresh fruit for beer, you DO need to take steps to sanatize, as wild yeast is definitely a factor in fresh fruit, and WILL sour your beer. Most people puree and boil. All it takes is about 40 seconds at a temp over 180 to sanatize fruit, so if you don't go the pre-packaged route, take those 40 seconds!