"Rye bread is not boiled."
Translation:Rugbrød koges ikke.
This could be another translation - I guess.
They do mean different things though but the ambiguity is in the English.
Rugbrød koges ikke. - Rye bread [is not meant to be | is not usually] boiled.
Rugbrød er ikke kogt. - Rye bread has not been boiled as part of its manufacturing process.
I hope this might be helpful, my vegetarian friend.