Professional chefs will tell you that baking is just as much science as it is an art. So what is the science of sugar? Each ingredient plays a part in the chemical reaction that happens when your cake, cookies, and pies go in the oven. Even tinkering with just one of the ingredients can affect whether you end up with a dry, hard imperfect creation or a flawless one.
Home bakers often assume that when they see sugar listed in a recipe, it’s just there for the sweetness. But there sugar provides more than just a sweet taste. There is clearly a science of sugar and it’s a versatile ingredient that plays a vital role in browning, rising, density and texture.
Sugar provides structure
How tall your cupcakes rise or how far you cookies spread is partially determined by a chemical reaction between proteins and starches. During the mixing process sugar bonds with water, taking moisture away from other starches and proteins present and limiting gluten development. When you mix your ingredients flour proteins are hydrated and form gluten strands. These highly-elastic gluten strands form thousands of small bubbles trapping the gases produced during leavening. When your dough or batter goes in the oven, the bubbles expand and stretch, allowing the dough to rise. By slowing gluten development, sugar helps give your final baked product a tender texture and good volume.
When your recipe has the proper balance of gluten, starch and sugar, it will have the right height and texture. Too much sugar and you could end up with droopy cinnamon bread. If you use too little sugar then too much gluten will develop leaving you with dense texture like a pretzel roll.
Sugar creates texture
Sugar easily binds with water, which accomplishes two main things. 1) It locks in moisture, keeping your baked goods from drying out; and 2) It inhibits the development of gluten which keeps your cookies, cakes and sweet breads softer.
Variances in sugar type will create different outcomes here. A brown sugar will lend more moisture than white sugar, because of the presence of molasses. Sugar also creates crunch in your baked goods. In the oven moisture evaporates from the surface of your treats, which allows the exterior sugars to recrystallize and brown.
Sugar facilitates leavening
Sugar makes yeast more effective by providing nourishment for its growth. When yeast breaks down sugar it speeds up the release of carbon dioxide gas. When these bubbles expand, the dough rises at a faster and more consistent rate.
Sugar adds color
Your baked goods get their golden-brown color from sugar. At about 175°C (or 347°F) sugar starts to caramelize, turning a warm amber color. During baking sugar, amino acids, peptides and proteins go through a process known as the Maillard Reaction. These reactions result in browning and produce wonderful smell associated with baked goods. The higher the sugar content, the darker golden brown the surface appears. This browned surface helps retain moisture and prolong freshness.
Sugar incorporates air
When sugar and butter (or shortening) are creamed together, the sugar crystals rub against the fat causing air pockets. When leavening agents are added, these air pockets grow larger. During baking, these air cells expand causing your baked good to rise. The length of time you cream your sugar and fat determines the total amount of air in the mixture.
Sugar serves as a whipping aid to stabilize beaten egg foams. In foam-type cakes, sugar interacts with egg proteins to stabilize the whipped foam structure. In doing so, sugar makes the egg foam more elastic so that air cells can expand and take up gases from the leavening agent.
Beaten egg whites or a meringue hold air bubbles because the mechanical action of the beaters partially coagulates the egg protein. When sugar is added, often with another stabilizer such as salt or cream of tartar, the protein film becomes more adhesive and its ability to hold air bubbles is increased. This results in a stiffer, higher and more stable foam.
Sugar gels and preserves
Sugar is essential in the gelling process of jams, preserves and jellies, providing consistency and firmness. This gel-forming process is called gelation – the fruit juices are enmeshed in a network of fibers. Pectin, a natural component of fruits, can only form a gel when combined with sugar and acid. Sugar is essential because it attracts and holds water during the gelling process.
Sugar also prevents spoilage of jams, jellies, and preserves after the jar is opened. Properly prepared and packaged preserves and jellies are free from bacteria and yeast cells until the lid is opened and exposed to air. Once the jar is opened, sugar incapacitates any microorganisms by its ability to attract water.
This is accomplished through osmosis (the process whereby water will flow from a weaker solution to a more concentrated solution when they are separated by a semi-permeable membrane). In the case of jellies and preserves, the water is withdrawn from these microorganisms toward the concentrated sugar syrup. The microorganisms become dehydrated and incapacitated, and are unable to multiply and bring about food spoilage.
So now you know the science of sugar and why sugar plays such a vital role in your baked goods; making this is one sweet science lesson! Put your science of sugar knowledge to work by checking out some of our newest recipes online.