My Agriscience Research Blog!: From Bitter to Sweet: How Sugar Content Changes in Ripening Fruit

Materials and Equipment

To begin, collect five unripe bananas. Choose five bananas that are similar in size and that are all unripe. The bananas should be as similar to each other as possible. The pieces of fruit should be unripe when you take your first reading at the start the procedure and very ripe for the last reading.
Read the directions that came with your refractometer.
On the day you purchase them, cut off a section of one of the unripe bananas that is about 3 inches in length.
Place the banana section on the plate and mash it thoroughly with a fork.
Cut a 6-inch square of cheesecloth.
Place about one-third of the chopped banana in the cheesecloth and squeeze out a few drops of juice onto the lens of the refractometer.
Squeeze slowly so that the juice has time to flow through the cloth. As an alternative, you can wipe the surface of the wet cloth on the glass of the refractometer.
Read the sugar content of the unripe banana. Record the data in a data table in your lab notebook. Be sure to note the trial number, condition of the fruit, date, and sugar content (in Brix). Discard the fruit in the cheesecloth.
Repeat steps 4–7 with the remaining freshly mashed banana two more times. Use new cheesecloth and banana for each reading. You should have three separate readings for each piece of fruit.
Repeat steps 4–7 for the remaining pieces of fruit, as they ripen, as follows. Note: You might want to modify the days on which you take your Brix readings, depending on how quickly the fruit is ripening.

Perform the entire procedure two more times. This demonstrates that your results are repeatable. The tests can be run concurrently.
Average the degrees Brix for each day and record these numbers in your lab notebook.
Graph the time, in days, on the x-axis and the degrees Brix on the y-axis.