Passage IV

As a banana ripens, the external peel changes color and the chemical composition of the internal pulp changes. Three experiments were performed to study the ripening of bananas.

Experiment 1

On Day 0, 100 bananas were harvested from the same banana plant. All the banana peels were completely green, so the average peel color "completely green" was assigned to the group. Next, the bananas were stored under ripening conditions (16℃ and 85% relative humidity) over the next 35 days. Every 7 days during that time period, the bananas were inspected and a new average peel color was assigned. The relationship between average peel color and time is shown in Table 1.

Experiment 2

On each day that an average peel color was assigned, the following procedures were also performed: First, 3 bananas were randomly selected from the group and peeled. Then, the pulps of the 3 bananas were thoroughly mixed together, and a 100 g sample of the pulp mixture was collected. Next, an 80% solution of ethanol in H₂O (by volume) was mixed with the sample to extract the starch and the sugars from the sample. Then, the mass, in g, of the starch in the sample and the mass, in g, of the sugars in the sample were determined (see Figure 1).

Experiment 3

On each day that the mass of the sugars in a sample was determined, the sugars were further analyzed, and the mass, in g, of each of the 3 sugars—fructose, glucose, and sucrose—in the sample was determined (see Figure 2).

Table and figures adapted from R. C. Adão and M. B. A. Glória, "Bioactive Amines and Carbohydrate Changes During Ripening of 'Prata' Banana (Musa acuminate x M.balbisiana)." 2005 by Elsevier Ltd.