When I was a teen, my grandmother lived with us in an in-law unit on the property. We had about 20 fruit trees and a large garden. Each year she would put up excess fruits, veggies, and sauces. She would write the year on the lid with a Sharpie pen. During the winter, we would eat from this pantry, oldest food first. It was not uncommon to be eating food from three or four years back. Tasted fine, looked fine. About 2% of the jars would loose their seal, but the safety button would pop up and be noticed, and we would simply toss the contents onto the compost pile. Also the jars were stored in a cool, dark, and dry place.