The narrator, adult Negi, is in her local Shop and Save examining the guavas. She inspects one that isn't quite ripe and describes its color and shape to the reader. She says that when you bite into a guava, you must be careful to not hit the seeds, as they get stuck in your teeth for hours. She says that as children, she didn't always wait for the guavas to ripen. Underripe guavas are hard and sour. Negi says that at night, Mami would make her drink castor oil while saying that castor oil tastes better than a green guava. Negi says that when she heard that, she knew she was a still a child, and knew her mother wasn't a child anymore.
Negi as the narrator makes it very clear from the outset that there are major differences between herself now, as an adult, and the child she once was. She also sets up that she and her mother are very different from each other. This suggests that as a child, Negi saw that there was a great deal of distance between herself and her mother, though it also leaves room for Negi to learn about Mami throughout the memoir.
Negi says she had her last guava on the day she left Puerto Rico. She ate it in the car to the airport. Today, in the Shop and Save, the guavas are $1.59 each and remind her of Puerto Rico, even though it's autumn in New York and she's an adult now. She puts the guava back on the display and pushes her cart towards the "predictably sweet" apples and pears.
Today, the guavas are a reminder of the identity that Negi seems to barely have anymore—rather than connect to her past by choosing guavas, she chooses "predictable" fruit. This introduces the idea that Negi struggles with an identity that isn't necessarily homogenous.