Everything will be removed and expiration dates checked. If it has expired it gets tossed, but short dated items (expires in a month or less) can be donated to the free clinic for immediate use. If you have more of an item than your family can use before expiration, donate that too.
When the shelves are clear wipe them down, then place your favorite brand of boric acid tablets (I like Harris Famous roach tablets) at the rear of the shelves. This should help control ants and other buggies.
Time to organize. Like items together and longest time before expiration to the rear. When you add new items place shift everything forward and place them in the back. It's tempting to throw things on the shelf when unloading in a hurry, but that's how this whole mess began.
This isn't a fun task, but play some music or listen to a book on CD while working. Think of how nice it will be to be able to find something in a jiffy and your family will have less of a tendency to grumble when you come home from the store after stocking up.