Fresh Cranberries Bounce Like Rubber Balls

The secret to a cranberry's surprising springiness lies within its structure. Each berry contains four small, hollow chambers filled with air. These pockets act as natural air cushions, giving firm, fresh fruit a unique elasticity. When dropped, these internal air pockets compress and then rapidly expand, launching the berry back into the air much like a tiny rubber ball. This same feature is also responsible for the berry's buoyancy, a trait crucial for the most common method of harvesting.

This unique physical property has been ingeniously exploited by growers for well over a century. To separate good fruit from bad, cranberries are often passed through a machine called a bounce board separator. As the berries tumble down a series of wooden planks, only the firmest, freshest ones have enough spring to bounce over the barriers into a collection bin. Softer, bruised, or rotten berries lack this bounce and simply drop into a separate channel for disposal. This simple yet effective mechanical test ensures that only the highest quality berries make it from the bog to your table.