Powdered sugar, although I’m pretty sure that’s not what you’re getting at. Lots of powdered spices as well, but I’m pretty sure they don’t apply either. Neither would flour or cornmeal.
I think the main things that lend themselves to powdering are ones that are liquid, like milk, or that are liquid before cooking. So with that in mind, milk and eggs are obvious, but things like powdered broth/bouillon, and powdered soups are probably available- I haven’t ever actually looked. Powdered buttermilk is definitely available for baking, and there are lots of drink mix powders as well.
I buy powdered milk for adding to bread dough to make it a bit richer. My bread machine also has a delayed start feature and if you want milk in that bread you have to use powdered.
Powdered eggs reminds me of camping with dad. Powdered milk reminds me of when I was a kid. Since I rarely (almost never) drink milk, I used to keep powdered milk so that I could mix some up when I needed milk as an ingredient.
Carnation still sells dry milk but the website only mentions its usefulness in baking. When I was a kid, one of the neighbor families had a lot of children but not a lot of money so the mother would use this stuff for drinking, mixed 50/50 with real milk. And my mother used it in a particular recipe.
The OP mentions the use of powdered eggs and milk in the military. Those were settings where refrigeration might have been unavailable, so the powdered stuff was useful for them. Today, refrigeration is available virtually everywhere, and then there is UHT milk that doesn’t need refrigeration.
I’ve never seen powdered eggs in a store, but I would imagine you could get them at a camping outfitter or a survivalist or bulk-foods store, and they’re definitely used for industrial cooking (like employee cafeterias) and packaged foods. But then again, I’ve never looked for them, either. This is what I’ve heard is done with lower-grade eggs, as one might imagine. They would be reconstituted and used like scrambled eggs or in baking, I guess.
I have some reconstituted powdered milk in my fridge right now. IMNSHO, instant powdered milk is dreadful, but mine is non-instant (bought on clearance because it was past its sell-by date) and tastes just like fresh skim milk. It actually mixes up in a matter of seconds, not just instantly.
Sometimes dried potato comes as flakes of little lumps, but I have also seen it as powder, and even had some quite recently. You can use it to make mash, but that is not very good. However, I use it in certain recipes where the real potato taste and texture would be submerged anyway, and using the dried stuff is a lot quicker than peeling, boiling and mashing.
