Who knew? The FDA legally allows up to a whopping 60 percent of canned or frozen berries to contain mold and still be sold in a supermarket. While many berries are perfectly fine to eat, to be absolutely sure your berries are free from mold, go fresh instead. When strawberries, raspberries and blackberries are in season, freeze them on a flat cookie sheet and store them in airtight containers. Only then do you know they are 100 percent free of mold.