Apples are a delicious fruit that last much longer than many other types of fruits. Eventually, though, your apples will start to rot. It is important to be able to spot an apple that is beginning to rot and remove it from your package of apples. This is because a rotting apple gives off ethylene. Ethylene will cause the other apples to rot much faster. Rotting apples won't taste good anyway, and they can even turn your stomach if you were to go ahead and eat them.
Squeeze the apple. Apples that are beginning to rot will give way when you squeeze them. A healthy apple will be firm when you press on it.
Take a look at the skin of the apple. Every once in awhile some mold or mildew will begin growing on the outside of the apple. It will appear light gray in color and may look like a powdery patch. This is not a healthy apple, and it is best if you don't eat it.
Cut the apple open. If you see a small brown spot, it is just a bruise. You can remove it and eat the rest of the apple. If you see several large brown spots, the apple is rotting. Don't eat it.
Keep away from any apple that is basically mushy and brown. Apples that have become rotten will be very mushy and brown in color.