Why do cranberries float and bounce?
Drop a fresh cranberry on the floor and it bounces. Drop it in water and it floats. Photos of cranberry harvests even show whole fields of red berries floating. What is going on inside that little berry? We traced the sources — and found a sorting machine that works by bouncing.
Cut a fresh cranberry in half and look inside: cranberries have four air pockets. Those air pockets let them float on water. That is why cranberries are harvested by knocking them off the plants into flooded bogs (the wet, sandy fields where cranberries grow).
Who says so: University of Wisconsin–Madison Extension (Wisconsin Harvest of the Month: Cranberries) (opens in a new tab)
The same air makes them bounce. A fresh berry will “bounce” when dropped, because small pockets of air inside a cranberry make the fruit bounce and float. When you pick cranberries at the store, look for ones that are brightly colored, smooth, shiny and firm, and skip the ones that are dried-up, soft or wrinkled.
Who says so: Penn State Extension (opens in a new tab)
Growers have used the bounce for more than a hundred years. At Whitesbog, an old cranberry farm in New Jersey, sorting machines shook the berries over a series of plates: good berries would bounce through and be collected in barrels, while rotten ones were left behind. Another common machine of the time let firm, good berries bounce down a series of steps. A chart from 1917 even compared sorting by “bounce machine” with sorting by hand.
Why would a berry need air pockets in the first place? A plant scientist explains that the pockets let the berries float down rivers and streams to spread their seeds. Many plants get their seeds carried around by birds and animals that eat the fruit. But raw cranberries are super sour, so wild animals aren't very interested. Floating is another way to travel.
Who says so: Serina DeSalvio, Texas A&M University (article in The Conversation) (opens in a new tab)
Even the name has a story. When a cranberry flower opens, its four petals peel back. The same scientist writes that the flower looks like the beak of a bird, which earned the plant its original name: the “craneberry.”
Who says so: Serina DeSalvio, Texas A&M University (article in The Conversation) (opens in a new tab)
Note: a “theory”, “folklore” or “outlook” is not settled fact. Always check who is saying it.
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