After 24 hours, the celery without the tubes should be much more limp than the piece with the tubes intact. Aluminum Trivia Kids, let's explain why chewing an aluminum foil spitball can really hurt some people, while for others it is just a weird piece of gum. The difference is because some of us have silver fillings in our teeth. It turns out that aluminum atoms lose their electrons very easily. In the presence of our mildly acidic saliva, which acts as a catalyst, we have what amounts to a crude electric battery.
Electrons flow from the aluminum to the silver amalgam filling.
Aluminum foil will begin to decompose in the presence of many other acidic substances in a process called oxidation. Acids like to oxidize obliging metals. Tell any cooks you know to never wrap a meatloaf glazed with ketchup or tomato sauce in aluminum foil for storage. After several hours the result of this contact is a grayish-black disgusting mush of aluminum oxide. Chemistry solves that problem, too.