Science Buddies: "Ask an Expert"

Im finishing my teaching certificate in physics secondary right now. I’ve completed the "How Sugar Content Changes in Ripening Fruit" using the suggested refractometer and I found that green bananas brix values only changed a small amount in the first day or two of checking and then steadily decreased as the banana ripened. Also, I found that the brix values were the same as ripe bananas are supposed to be when very green (19+). (From online charts this is supposed to be for perfectly ripe bananas that are very much yellow.) I checked brix every other day in a very clean environment cleaning the tester thoroughly between each test, I kept the room at around 78 degrees Fahrenheit and tested the bananas five times. I also ran five trials of the experiment. One possible solution I have found (with very little research to support it)I recently read that most bananas that are sold in the US and the world are now artificially ripened using ethylene gas. Could this account for the results? Most research I have read states that bananas should naturally increase brix as they ripen because of a hormone that is released causing the starch in the banana to convert to a sugar. Something isn't right here... ( two trials I did with the bananas sitting close together to see if ripening increased while keeping the ones in the other trials far apart. the bananas appeared on the outside to ripen faster but the brix was usually about the same as the separated ones.)

Any ideas would be greatly appreciated.

This is confusing, but I like your idea about artificial ripening. Brix can decrease as a result of fermentation, perhaps that is what is happening?

Cheers,
Colin