Temperature affects the decomposition of rotting bananas in two ways. Lowering the temperature by refrigerating or freezing slows or halts the decomposition process, while increased temperature speeds up the decomposition process.
Temperatures below 40 degrees Fahrenheit inhibit bacterial growth. Placing a banana in the refrigerator will help to slow the decomposition process. If you place a banana in the freezer, it will halt the decomposition process. It is the water content of the banana that allows microbial growth and chemical reactions to occur. Freezing changes the water in the banana from a liquid to a solid, thereby not allowing any chemical reactions to occur. Bacteria and molds require water to dissolve the food they use for energy and growth, as well as to release their waste products.
In contrast, if you raise the temperature of the environment in which a banana is rotting, it will decompose even faster as the heat and increased moisture in the air encourages bacteria and mold growth and increases the rate of natural food enzyme reactions. If your home is hot or humid, it is best to keep fruits and vegetables in the refrigerator to ensure they stay fresh longer. However, refrigerated fruits can lose many of their qualities.