The following is a short general explanation of which foods are included in “pat” – bread – and would have the halachot of pat akum. Only foods made from the five types of grain are included. The five grains are wheat, barley, spelt, oats, and rye. Foods made from corn flour or rice flour are not included in pat.
If the food is a mixture of flours that are from the five grains and flours that are not from the five grains, the food has the status of the flour which is the majority.
If the flour is in the recipe as a thickener and not for taste (such as in twizzlers) then the flour is secondary to the food, and the food does not have the rules of pat akum.
Pat only includes foods which one would be required say birkat hamazon after eating them. Included in this is pat haba bekisnin, meaning a snack which is of the type that can also be eaten as a meal. Such a snack (such as a croissant) is mezonot, but if enough would be eaten to be considered a meal, one would be required to wash and make a hamotzi on the food.
According to the Shach (יו”ד סי’ קיב ש”ק יח) food made from a batter (as opposed to a dough) is not included in pat akum. The Torat Chatat brought in the Shach explains that one does not make a birkat hamazon on foods made from batter. The Chelkat Binyamin (סי’ קיב ס”ק סד) writes that most poskim disagree with the Shach, and baked products made from batter are included in pat akum.
Deep fried foods, such as doughnuts, are not included in pat akum, unless it was baked after the frying, because no matter how many doughnuts one eats, they would not be required to recite birkat hamazon.