Is digesting a banana a chemical change?

Answer 1

I suppose so, it would be more correct to say it was due to a cellular change. Enzymes present in fruits, mainly polyphenol oxidase cause the browning in damaged fruit. Normally polyphenol oxidase works in plants as a defense against insects. When activated this enzyme turns phenols in the plant into quinones, these quinones then turn into melanins which have beneficial properties to the plant as an antibacterial, anti-fungal, and UV protection. Melanins are dark in color and so make the areas where they are present appear brown.

In healthy plant tissue the phenolic compounds are stored in the vacuole of the cell, well separated from the polyphenol oxidase enzyme so no activity happens. However, when a banana is bruised by dropping onto a hard surface or simply overripening, the cells become damaged, the separating membranes are ruptured and polyphenol oxidase can access the phenolic compounds and start the process of turning them into quinones and then into melanins, making brown and black spots in the damaged areas.

Answer 2

Yes because you cant get the banana back to its original state. As the banana is digested, the waste then becomes excrement.