mechanical

• we can add air to mixtures through folding
• to fold a cake mixture, you carefully use a spoon or spatula to repeatedly pour the liquid mixture over itself - trapping air each time
• pastry doughs can actually be folded into layers, trapping air in between the layers each time you fold
• beating is a more vigorous method where you use a spoon or fork to mix ingredients and quickly drive air into the mixture
• whisking is the same as beating, but you use a whisk instead
• when you sieve flour, air becomes trapped between the individual flour particles
• air is also added when creaming, and between flour particles when you rub fat into flour