The Properties and Uses of Corn Syrups

Appears in
On Food and Cooking

By Harold McGee

Published 2004

  • About
Among the usual sweeteners available to the cook, corn syrups are alone in providing long carbohydrate molecules that get tangled up with each other and slow down the motion of all molecules in the syrup, thus giving it a thicker consistency than any but the most concentrated sucrose syrups. It’s largely these long tangly molecules that have made corn syrup increasingly important in confectionery and other prepared foods. Because the tangling interferes with molecular motion, it also has the valuable effect of preventing other sugars in candy from crystallizing and producing a grainy texture. All molecules in the syrup are flowing very slowly, and the sucrose crystal faces keep getting covered with chains that can’t become part of the crystal. (The same behavior helps minimize the size of ice crystals in ice cream and fruit ices, thus encouraging a smooth, creamy consistency.) Another consequence of corn syrup’s viscosity is that it imparts a thick, chewy texture to foods. And because it includes glucose, a water-binding sugar that is less sweet than table sugar, corn syrup helps prevent moisture loss and prolongs the storage life of various foods without the cloying sweetness that honey or sucrose syrup imparts. Finally, all corn syrups are somewhat acid, with a pH between 3.5 and 5.5, so in baked goods they can react with baking soda to produce carbon dioxide and thus contribute to leavening.