So each bread supposedly corresponds with each class.
Soldier: ration bread
Heavy: russian black bread
Pyro: burnt slice of bread
Engineer: cornbread
Spy: baguette
I'm going to guess that the pretzel is Medic, crumpet is demo, then cinnamon and plain bread for either scout or sniper?
(By the way this is all my thoughts over this bread stuff and not anything cannon. Is it a random piece of bread spawned or does the corresponding one appear when you teleport?)