Why does it smell like rotten fruit?

The smell of rotten fruit is primarily due to the breakdown of sugars and other compounds by bacteria and fungi during the fermentation process. As fruits decay, they release volatile organic compounds, including esters, aldehydes, and alcohols, which contribute to the unpleasant odor. Additionally, the production of gases like ethylene can also intensify the smell. This combination of factors creates the characteristic scent associated with overripe or spoiled fruit.