Most fruit has a lot of water in it, so when you freeze fruit, you are freezing the water inside of it. Water actually expands (gets bigger) when it freezes, which can cause problems for freezing fruit. If you were to look at various fruits with a strong microscope, you would see that they are usually made of small “bags” (called cells, or things like cells), which are filled with water and other stuff.

Sometimes, when you freeze fruit, the water inside those bags gets bigger, and breaks the bags! When the fruit thaws out, it is not always the same — strawberries are mushy, because the “bags” are ruptured. Try eating some frozen blueberries, or putting them in your breakfast cereal. The milk, and your tongue, will turn purple-blue. If you eat fresh blueberries (or put them in your cereal), this does not happen — the milk stays white, and your tongue stays pink. The reason? The molecules that make blueberries blue are trapped in those little bags. Freezing blueberries breaks the bags, so when they thaw out, those blue dye molecules escape and stain your tongue!

Believe it or not, liquid fabric softeners like Downy often have the same kind of structure: little bags inside of bags inside of bags. Try taking some Downy, freezing it, and then thawing it back out. It will never be the same...

Ice crystals form inside of the fruit cell cytoplasms, which tear apart the cell walls. This causes the fruit to become squishy and mushy because the cell walls that hold it together can no longer do their job.

All living things are made of cells. Cells have a lot of water in them. When water freezes, it expands (gets bigger). This breaks the wall of the cells.

That is why fruit gets mushy when you freeze it. The water thaws out and shrinks again, but the cell walls are still broken.

Do you think all fruits have the same changes when you freeze them? An adult may be able to help you experiment with this.