Flour is a mixture of several types of macromolecules. Macromolecules are large molecules and are often polymers, or bigger molecules made up of many smaller molecules, known as monomers. The most common types of naturally occurring macromolecules are:
- polysaccharides - includes starches and cellulose (fiber)
- polypeptides - proteins, which are made of amino acids
- lipids - fats and oils
- nucleic acids
There are different types of flours, and their properties differ based on composition. Refined white flour is mostly starch molecules. These macromolecules are called polysaccharides because they're made of long chains of chemically joined monosaccharide (sugar) molecules. There's a small amount of protein and fat in white flour. Higher gluten flour, which is used for crispier, chewier bread has more protein than "soft" flour that's used for cakes and cookies.
Whole wheat flour has more protein and fat than white flour and also contains some nucleic acid molecules from the wheat germ.