When it comes to testing whether a cranberry is fresh or not, just copy the professionals. Cranberry growers have a simple test to see whether a cranberry is ready to be harvested. They will bounce the cranberry. If the cranberry is ripe, it should bounce high enough to go over a small fence. If it is not quite ripe, then the cranberry will not bounce. This is due to the fact that cranberries grow air pockets when they become ripe, which in turn allows them to bounce.