Substitute for Altbrot?
Many German and Austrian rye bread recipes specify the use of Altbrot ("old bread") in a hot soaker. The Altbrot adds a creaminess and a better shelf-life (anti-staling) to the bread.
My problem is that I rarely have any leftover rye bread or it's a bread that may not be the best choice as an Altbrot (e.g., Ginsberg's Sauerkrautbrot from The Rye Baker).
I have seen store-bought bread crumbs suggested and I do have some of those I can use, but I'm looking for other suggestions for substitutes in those instances I don't have any Altbrot.