And even if we did have nutritionally stable food for this long, there's a growing amount of evidence that even just mechanical food processing is enough to make it _unhealthy_ – if it comprises the majority of your consumption – and that it causes metabolic problems (irrespective of additives). And that's on Earth.

If we are to eat just processed food in space, we'll need a lot more research on this. It would be better if we just grew food from plants.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8747021/