What Sugar Does in Baking: Six Functions Beyond Sweetness

If you’ve ever tried to remove sugar from a baking recipe, you know it doesn’t just taste less sweet. Something structural changes too. Cookies don’t brown properly. Cakes are dense. Quick breads go stale faster. You removed one ingredient but broke several things at once.

Sugar isn’t just flavor in baked goods. It’s doing physical and chemical work.

Function 1: Browning

Sugar participates in two separate browning reactions that occur during baking.

The Maillard reaction requires a reducing sugar and an amino acid. Sucrose (table sugar) is not itself a reducing sugar, but it hydrolyzes into glucose and fructose (both reducing sugars) in the slightly acidic conditions of most batters and with heat. These reducing sugars then react with the amino acids in eggs, milk, and flour proteins to produce the hundreds of flavor and color compounds that give a golden-brown cookie or cake its characteristic flavor.

Caramelization is a separate reaction that happens to sugars alone at high temperatures, without protein involvement. Sucrose starts to caramelize at around 320°F, producing a range of compounds (caramels, furans, diacetyl) that add color and complex flavor. In oven-baked goods, crust surfaces often reach temperatures where caramelization occurs alongside the Maillard reaction.

Both reactions require sugar. Less sugar means less browning from both pathways. Reduced-sugar baked goods are often noticeably paler and less flavorful even when adjusted with other flavorings.

Function 2: Moisture Retention

Sugar is hygroscopic, meaning it attracts and holds water molecules. Dissolved sugar in a batter or dough binds moisture, resisting evaporation during baking and reducing moisture migration after baking.

The practical effect: higher-sugar baked goods stay moister longer. A standard chocolate cake (often 1:1 or higher sugar-to-flour by weight) stays moist on the counter for days. A low-sugar version goes stale much faster because the water in the crumb is free to migrate and evaporate.

Brown sugar is more hygroscopic than white sugar because molasses contains invert sugar (a mix of glucose and fructose) plus acids and other compounds that attract moisture even more aggressively. This is why recipes specifying brown sugar often produce consistently moister results.

Honey and corn syrup (which contain glucose and fructose in forms that resist crystallization) are even more hygroscopic than sucrose. Baked goods made with honey or corn syrup as part of the sweetener tend to have notably moist textures that last longer.

Function 3: Tenderizing

Sugar tenderizes baked goods by two mechanisms.

First, sugar competes with flour proteins for water. Proteins need water to hydrate, uncoil, and develop gluten. If sugar is absorbing some of that water, less is available for gluten development. Less gluten means a more tender crumb. This is the same interference principle as in fat in baking, just achieved differently.

Second, sugar delays starch gelatinization. Starch granules absorb water and swell at temperatures above roughly 140°F, setting the structure of baked goods. Sugar in solution slows this process, meaning the batter stays more fluid for longer during baking. That allows more leavening gas to expand before the structure sets, and the final texture is lighter and more tender.

This is why high-sugar cakes have a soft, fine crumb even with significant flour content. The sugar is essentially fighting the structure-setting that starch and gluten would otherwise produce.

Function 4: Aeration in the Creaming Method

In any recipe that starts with creaming butter and sugar, sugar is acting as a physical aerator. The sharp crystals of granulated sugar cut tiny air pockets into the butter matrix during beating. The fat holds those air cells stable.

When the batter bakes, those air pockets expand with heat and CO2 from leaveners, producing lift. This is a primary leavening mechanism in layer cakes. No sugar means no sugar crystals means no air incorporation, which means less rise and a denser crumb even with chemical leaveners present.

Powdered sugar (confectioner’s sugar) doesn’t cream as effectively as granulated sugar because the fine particles don’t cut air pockets as efficiently. It’s used in shortbread and some icings, but not in standard cake batters for this reason.

Function 5: Yeast Nutrition

In yeasted baked goods (breads, brioche, cinnamon rolls), sugar feeds the yeast. Baker’s yeast (Saccharomyces cerevisiae) consumes available sugars and produces CO2 for leavening. The sugars in plain flour are limited. Added sugar extends the fuel supply and speeds fermentation.

At low concentrations (1-5% of flour weight), sugar accelerates fermentation. At higher concentrations (above 10-15%), the osmotic pressure of the dissolved sugar inhibits yeast. This is why very sweet doughs like panettone and babka require more yeast and sometimes osmotolerant yeast strains to achieve adequate rise. See more in yeast leavening science.

Function 6: Crust and Structure

Sugar at the surface of baked goods caramelizes and creates a glossy, crisp crust. Cookie tops that turn glossy and crinkled (like brownie tops or sugar-glazed cookies) achieve that through surface sugar concentration and Maillard browning at the crust.

In yeast breads, even a small amount of sugar in the dough contributes to crust color. Lean breads with no added sugar (like baguette) develop crust color more slowly and primarily through starch surface reactions. Enriched breads with 5-8% sugar brown faster and more evenly.

Sugar also contributes structural integrity in some applications. Meringue is mostly sugar in whipped egg whites: the sugar reinforces the foam structure by increasing viscosity and later crystallizes into a rigid matrix when dried. Fudge and candy are almost entirely sugar, and the texture is controlled entirely by crystal size during cooling.

Removing sugar from a recipe isn’t a simple substitution. It’s removing a compound that’s doing six different jobs simultaneously.