What’s with a banana’s spots? (BioE80 Spr2015)


We were curious about how bananas brown: from the outside in our inside out? Does the browning equally affect all layers of the banana? Are the spots the same pattern throughout the bananas? We were primarily trying to explore questions in this range of spot depth, uniformity, and formation. We decided to pick a lightly browned banana and examine its skin in depth. We peeled apart the skin into more than 5 very thin layers and placed them on slides and used our foldoscope to analyze each one. We found that the outermost layer (pictured above) exhibited browning to the same degree as the innermost layer of skin. By this we mean that the spot pattern was indeed the same. You can also see in the picture above that the color of the browning was very light. The color was lighter than when we observed the banana with its skin intact; this indicated to us that the layering of the skins increases the intensity of the color, thus further supporting our thoughts that the spots must be somewhat uniform from layer to layer. Our data did not directly answer our question about spot growth direction, but it provided valuable insight into the depth of browning. Banana browning is indeed penetrative and at least somewhat uniform through layers of the banana by our experimentation. To figure out the exact direction in which that happens, and also how different elements (oxygen,water) might affect the process, we’ll just have to do more exploring!


Contributors  — SUnet ID:

Sukhi (Shabnum) Gulati — sgulati3

Joe Carpenter — jcarpent

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