The activity of water (a function of the chemical potential) in ketchup is very low. If the water activity of a food is low enough it'll keep without refrigerat

The activity of water (a function of the chemical potential) in ketchup is very low. If the water activity of a food is low enough it'll keep without refrigeration. I don't know if ketchup's low enough to stay indefinitely, but it'll keep long enough. https://en.m.wikipedia.org/wiki/Water_activity https://en.m.wikipedia.org/wiki/Water_activity