I have a bread box with a drop down lid.. And then I set a trap. I took a kitchen towel with all of mine as babies, that had a can of like pebbles or coins- something that would make a heck of a lot of noise, wiped my hands in raw chicken ( then washed them of course) but left the towel on the counter with the can inside, and left the room.. At the crash come in like " what happened here??/ HUH HUH??".. My dogs will leave a kitchen towel alone for this reason. .. so you could do this then put the kitchen towel over the bread if you cant watch them.
However - my concern is- if they can get bread, what else can they get that is not so harmless?