Even in the hypothetical scenario where all vegetables and meat have shelf lives of a year, it still wouldn't make that much of a difference when it comes to food security. Products with long shelf life are sold with that long shelf life. This does mean that any kind of failed harvest means that those products will either disappear out of the selection or a different formula is used to maintain availability. Companies dont store anything, governments only store rice and grains at most since they are the only economically feasable types. Citicens will actively induce food shortage once there is one.

All you're left with is figuring out how much food is between the harvest and the supermarket. And that's not alot. Demand matches the consumption of citizens and time to market is optimised to be short. This is before considering how unhealthy the most durable foods are since sugar is the main ingredient in all of them, from chips and chocolate to processed cans.