What causes a banana to turn to liquid on the inside?

A banana turns to liquid on the inside primarily due to enzymatic breakdown during ripening. As the fruit ripens, enzymes like amylase convert starches into sugars, and pectinase breaks down pectin, leading to the softening of the fruit's structure. If the banana overripes or is damaged, this process accelerates, resulting in a mushy, liquid-like consistency. Additionally, excessive moisture and heat can also contribute to this process.