How to Freeze Overripe Bananas
If bananas have turned brown and are too ripe to eat out of hand, don't throw them away. Peel and mash them, stirring in 1 tsp. lemon juice for each banana. Freeze in an airtight container for up to 6 months. Thaw the banana purée in the refrigerator, then use to make banana bread, banana cake or muffins.