Final answer:
Cake flour is used for softer and puffier cookies because it contains less protein, leading to less gluten and a finer crumb. Heat-induced gas expansion during baking, as explained by Charles's Law, also contributes to the texture of baked cookies.
Step-by-step explanation:
Cake flour is preferably used to make soft and puffy cookies due to its lower protein content compared to all-purpose flour. The reduced protein in cake flour results in less gluten formation when mixed with wet ingredients, which in turn makes the cookies tender. In addition, cake flour has a finer texture, which contributes to a finer crumb in baked goods, enhancing the softness.
Furthermore, the science of baking involves chemical reactions. When ingredients like flour, butter, sugar, and baking soda are combined with eggs and exposed to heat, the resultant cookies are a product of these reactants. The process described in Charles's Law explains how gases like carbon dioxide expand when heated, which helps create the rise in doughs and batters. This is similar to the action of yeast in bread dough, which produces carbon dioxide to make the bread light and fluffy.