Besides its pleasant sweetness, sugar performs a host of less-obvious and important functions in cooking, baking, candy-making and the like.
Flavor Enhancement — Sugar "potentiates," blends and balances flavor components, much like a seasoning. For example, a pinch of sugar added to corn, carrots and peas produces a better-tasting product. In most tomato based products, such as barbecue, spaghetti, and chili sauces, sugar softens the acidity of the tomatoes and blends the flavors.
Solubility — Sugar is readily soluble in water. The ability to produce solutions of varying degrees of sweetness is important in many food applications, particularly beverages and confectionery. Sugar’s capacity to produce a supersaturated solution and then crystallize when cooled is the basis for rock candies. The wonderful variety of confectionery draws from the candy maker’s ability to vary sugar concentration, along with temperature and agitation, to produce different crystal sizes and textures.
Boiling Point Rise, Freezing Point Depression — In solution, sugar has the effect of lowering the freezing point and raising the boiling point of that solution. These are important properties in preparing frozen desserts and candy, respectively. In ice cream, for example, sugar’s ability to depress the freezing point slows the freezing process, promoting a smooth, creamy consistency. In shortening-based cakes, sugar raises, delays and controls the temperature at which the batter goes from fluid to solid, which allows the leavening agent to produce the maximum amount of carbon dioxide. The gas is held inside the air cells of the structure, resulting in a fine, uniformly- grained cake with a soft, smooth crumb texture.
Hydrolysis (inversion) — In food processing, hydrolysis decreases the tendency of sugar to crystallize in thick syrups or jellies.
Caramelization (thermal decomposition) — When sugar is heated to a sufficiently high temperature, it decomposes or "caramelizes." Its color changes first to yellow, then to brown, and it develops a distinctive and appealing flavor and aroma. The melted substance is known as caramel. The brown color of toasted bread is the result of caramelization.
Browning (Maillard reactions) — Color is also produced in cooking when sugars and proteins interact in complex ways. This is known as the browning (Maillard) reaction, important in candy making, baking and other processes.
Yeast Fermentation — Sugar is consumed by yeast cells in a thoroughly natural process called "fermentation." Carbon dioxide gas is released, and alcohol is produced, reactions vital to bread rising and baking and alcoholic beverage production.
Bodying/Bulking Agent — Sugar imparts satisfying texture, body, mouthfeel and bulk to many processed foods, such as ice cream, baked goods, icings, beverages and candy.
Texture Modification — For example, as sugar is creamed with shortening in baked goods, the irregularities of the of the sugar crystals help create air pockets that contribute to a uniformly fine crumb structure. In gingersnaps and sugar cookies, the desirable surface cracking pattern is imparted when sugar crystallizes by rapid loss of moisture from the surface during baking.
Preservative — By binding water, sugar acts as a very effective, natural preservative. For example, the high sugar levels in jams, jellies and sauces make them more immune to the microorganism development common in thinner, high-moisture products like commercial applesauce. Sugar is the preferred sweetener in cereal coatings because of its ability to crystallize into a frosty surface forming a hard, continuous glaze. This protects the product from air and moisture, extending its shelf life.
Dispersant — In dry beverage, dessert and bakery mixes, sugar prevents lumping and clumping when the mix is hydrated.
Whipping Aid — In foam-type cakes, such as angel and sponge, sugar enables the creation of a light foam that serves as the basic structure of the cake.
Humectant — When the sucrose molecule is "inverted", by the application of heat, acids or enzyme, the resulting fructose (especially) and dextrose contribute a moistening property, desirable in such foods as icings, fudge, cakes, marshmallows, soft cookies, and so forth.
Microwave Properties — Sugar has unique dielectric properties that enable it to produce desired surface browning and crisping. Sugar can shield lower food layers from heating, as in microwavable ice cream toppings. Sugar can function as a control agent to minimize uneven heating.