I was wondering about putting things from the grocery store into canning jars and #10 cans. Can you do this and will they last 5 years or more? How do you know what you can do? I was thinking about Lucky Charms and shredded wheat cereal, cocoa powder, au graten potatoes with cheese pack inside and those packs of mushrooms, rice and pasta that has all the seasonings inside.
Yes, you can repackage foods you buy at the grocery store. I don’t know what foods you have in mind, but things like cereal and pasta will have a longer shelf life if sealed in canning jars (using one of those Food Saver jar attachments) or in #10 cans if you have access to that equipment.
Even when packaged in a better environment, some foods naturally have a shorter shelf life, so be sure to label the jar/can with the food and the date it was sealed. Pasta, for example, doesn’t last forever, like wheat or rice. You could also use those Food Saver bags to vacuum pack food.
The processed foods you mention, such as Rice-a-Roni, will last longer, but still, not super long-term just because of their refined nature. Remember the enemies of food: light, heat, humidity, pests, and oxygen. Repackage in an oxygen-free environment, store in a dry, dark place, and you’ll be adding to their shelf life.
Off the top of my head, I can’t think of any grocery store food that can’t be repackaged for a longer shelf life.