Why Frozen Bananas Taste Sweeter Than Their Countertop Counterparts

Take any banana, put it in the freezer for a few hours or overnight, and magic happens. The banana becomes even sweeter. This isn't magic, though; it's food science! Just like other plant, animal, or microorganism matter, bananas have cells that continue to live after harvesting. Enzymes are housed within these cells, and they can cause ripening, flavor changes, and nutrient loss when activated. All of these processes contribute to breaking down food into a simpler form, and the enzyme amylase in bananas is responsible for converting starches into sugar.

When a banana reaches a low enough temperature in the freezer, the water within the banana's cells expands and forms ice crystals. The cell walls rupture, and amylase is released. Although amylase is now ready to do its job and turn all the starch molecules into sugar, the cold temperature inhibits this action. Once the banana starts to thaw — whether it's coming to room temperature, exposed to heat coming from the blades of a blender, or simply warming in your mouth — this is when the amylase conversion accelerates rapidly. The result is a banana that tastes markedly sweeter than when it first went into the freezer.

Bananas don't necessarily need to be put in the freezer for this enzymatic reaction to occur — we've all seen what can happen when fresh bananas are neglected on the countertop for a few days. Even when bananas are kept at room temperature, amylase will still activate, playing a crucial role in ripening and making them taste sweeter. 

If you're thinking that freezing overripe bananas might make them even sweeter at this stage, it depends on how overripe the banana is when put in the freezer. Amylase activity will come to a halt once there is no more starch left for the enzyme to convert into sugar. However, you can still throw those overripe bananas in the freezer because you'll be preserving the sweet flavor that the amylase already created. This is one of the reasons why you should use frozen bananas for banana bread or banana pudding pops.

I personally find that bananas that are frozen when perfectly yellow or with some brown speckles come out of the freezer with an incredible natural sweetness and still have a toothsome bite when not entirely thawed. This is the best of both worlds when using them to create frozen treats, such as frozen banana chips dipped in chocolate and sprinkled with your favorite toppings or a blended ice cream-like dessert.