How can a bread have an expiration date of one year into the future?? The bread in questions is Deutsche Küche rye bread (from Aldi). Yes, it is a dense bread, but it is not dry like a cracker, so there seems to be enough moisture for mold to grow. There are no preservatives.
Edit (pictures added):
It's the baking and packaging.
These dark rye breads are baked for a very long time (effectively pasteurizing them) and then sealed in their packaging. If you do this in a commercial setting that can ensure a mostly contaminant-free environement, such breads can last a long time.
Once you break the seal by opening the pack, your bread will get moldy like all other breads.
The very dense crumb structure and compounds in the whole-grain rye used might to a certain degree inhibit the growth of mold, but not enough to make the bread last for months.
It's not so much one thing as it's multiple things working together to allow food to be packaged for long-term storage.
German food scientist Lothar Leistner came up with what he called "hurdles" that result in the preservation of food. For instance, for an air-dried ham, you have multiple steps that all lower the chance of spoilage, although no one on its own is enough: https://www.sciencedirect.com/science/article/abs/pii/S0924224400889414 https://link.springer.com/chapter/10.1007/978-1-4615-0743-7_2
... so you work at cold temperatures, lower water activity (by mechanical or chemical means), lower pH, work in a clean environment, sterilize the outside of the food (blanching, washing cheese, smoking, etc), replace the air in the packaging, etc.
This helps to explain why historical preservation techniques like confit or air-dried hams work when they'd be considered 'risky' by modern standards.
