This was first discovered by a man with a wooden leg! Due to his handicap, John "Peg-Leg" Webb couldn't carry his berries down from the loft in his barn. Instead, he simply poured the lot down his stairs!
It wasn't long before Webb noticed that only the freshest and firmest fruit bounced all the way down - any berries that were softer and bruised didn't make it to the bottom. This serendipitous discovery led to the invention of the bounce board separator, a device still used today to judge the quality of cranberries!