The difference between doughs and batters is reflected in their names. Dough comes from a root meaning “to form,” while batter comes from a root meaning “to beat.” Doughs are firm enough to develop and sculpt by hand. Batters are too fluid and elusive to hold, so we contain them in a bowl, mix them by battering them repeatedly from within—by stirring— and cook them in a container to give them form and solidity.
Batters are fluid because they include two to four times more water than doughs. The water disperses the gluten proteins so widely that they form only a very loose, fluid network. When we cook a batter, the starch granules absorb much of the water, swell, gelate, leak amylose, stick to each other, and thus turn the fluid into a solid but tender, moist structure. The gluten proteins play a secondary structural role, providing an underlying cohesiveness that prevents the food from being crumbly. But if the gluten is overdeveloped, it makes the food elastic and chewy. Batters often contain eggs, and the egg proteins also contribute a nonelastic solidity when they coagulate in the cooking heat. Fluid batters can’t retain much of the gas slowly evolved by yeast, and are usually leavened either chemically, or else mechanically, by beating air into the batter or its components.