When I was young - lets's say about 50 years ago - you only could get few different breads in bakery:
- "Paderborner", the 'normal' everyday bread (with about 79% rye flour in it)
- "Kasseler", which has less rye
- "white bread" (wheat)
- "raisin bread" (a sweet white bread with only little rye flour in it)
- and a baguette-like bread.
Only very few bakeries made Pumpernickel, because the oven had to be used all day for just one kind of bread. (So you got it in others packed from those bakeries.)
Until today, just three larger bakeries are left, who produce Pumpernickel in the original, traditional way: one in the town where I live (I don't eat their Pumpernickel because we got it [tinned] in the navy), then the one CJ showed (it was nearly unknown until about 25 years outside the production place) and then the one where it's produced since 1570 (that's the one, you still get in local bakeries - the business is in same family since it's beginnigs)
Their Pumpernickel is only made from rye, water and a little bit of salt
"Backed for 24 hours at 100°C in water vapour. The bread sold locally, is just wrapped in 'silver paper', you can store it some months.
When pasteurised, like this package ...
... it's fresh for one year and more.