Task: Question Generation
Input (English): Angel food cake, or angel cake, is a type of sponge cake made with egg whites, flour, and sugar. A whipping agent, such as cream of tartar, is commonly added. It differs from other cakes because it uses no butter. Its structure comes from whipped egg whites known as a protein foam. Angel food cake originated in the United States and first became popular in the late 19th century. It gained its unique reputation along with its name due to its light and fluffy texture, said to resemble the ``food of the angels''.
Output (English): is angel food cake batter supposed to be foam?