Yes, removing banana stems before storage can help slow down the ripening process and potentially extend their shelf life by preventing ethylene gas from spreading as quickly.
Bananas release ethylene gas, a natural plant hormone that triggers ripening. The stem is a primary source of this gas. By separating bananas from the bunch and removing the stem (or covering it tightly), you reduce the overall ethylene exposure. This can slow down the ripening process, giving you a bit more time before they become overripe. Separating the bananas also prevents the ethylene gas from one ripening banana from affecting the others in the bunch. You can further slow ripening by storing bananas away from other fruits that produce ethylene, such as apples and avocados.
Wrap the banana stems (either individually or the entire bunch stem) tightly with plastic wrap. This creates a barrier that helps contain the ethylene gas and further slows down the ripening process.