There are many factors involved here. How they are canned ( in canning jars not cans), how fast they are cooled, how tight they are sealed, and temp they are kept at. Anyone storing in a cellar where it is cool, dark and dry can save thiers longer than those that dont. The length of storage also depends alot on the acid content of the food. We have stored potatoes, peas, green beans, carrots, etc. for 3 years or more and have eaten them, meats for same, I have found that tomatoes change consistancy and flavor after 1-1 1/2 years, whereas fruits do the same, (tomato is actually a fruit LOL) But the difference is some get better, like apple butter. The older the better. Many dont like the way old fruit discolors (gets darker) but I find generally the taste gets richer for some things. Generally speaking around my house, if the seal is good, there is no mold, odd odor, color or consistancy it gets eaten. My wife generally recycles the jars, for another round on most things every two years. Every year on some things.