The Four Basic Food Molecules

Appears in
On Food and Cooking

By Harold McGee

Published 2004

  • About
This chapter describes the characters of the four chemical protagonists in foods and the cooking process, the molecules referred to constantly in the first fourteen chapters.
  • Water is the major component of nearly all foods—and of ourselves! It’s also a medium in which we heat foods in order to change their flavor, texture, and stability. One particular property of water solutions, their acidity or alkalinity, is a source of flavor, and has an important influence on the behavior of the other food molecules.
  • Fats, oils, and their chemical relatives are water’s antagonists. Like water, they’re a component of living things and of foods, and they’re also a cooking medium. But their chemical nature is very different—so different that they can’t mix with water. Living things put this incompatibility to work by using fatty materials to contain the watery contents of cells. Cooks put this quality to work when they fry foods to crisp and brown them, and when they thicken sauces with microscopic but intact fat droplets. Fats also carry aromas, and produce them.
  • Carbohydrates, the specialty of plants, include sugars, starch, cellulose, and pectic substances. They generally mix freely with water. Sugars give many of our foods flavor, while starch and the cell-wall carbo hydrates provide bulk and texture.
  • Proteins are the sensitive food molecules, and are especially characteristic of foods from animals: milk and eggs, meat and fish. Their shapes and behavior are drastically changed by heat, acid, salt, and even air. Cheeses, custards, cured and cooked meats, and raised breads all owe their textures to altered proteins.