As an aspiring product developer who wants to one day contribute to the creation of healthier processed foods, the aim of a lot of my baking experiments is to create low-to-no added sugar baked goods that are still magically delicious. Generally, there are two types of sugars — those that are naturally occurring such as the fructose in fruit and the lactose in milk versus those that are added to foods during processing or preparation such as white and brown sugar, and liquid sugars such as honey and maple syrup.
The white sugar commonly found in most pantries is sucrose, a disaccharide made up of two monosaccharides — glucose and fructose. Sugar is a carbohydrate and contributes to 4 calories per gram. Added sugars generally have no added nutrients and are thus considered empty calories. Consequently, it is suggested that their intake be limited. It is common knowledge that the consumption of excess calories will lead to weight gain which in turn is a risk factor for obesity, diabetes, heart disease, etc. More recently, a study published by JAMA Internal Medicine found that increased sugar consumption led to an increased risk of cardiovascular disease (CVD) mortality. Without getting into too many details of the study, the overall take home message shouldn’t be to eliminate all sugar from your diet, but to be more conscious of the types of sugar you’re putting into your body and as with everything else, consume sugar in moderate amounts relative to a well-balanced, healthy diet.
Aside from sugar’s non-nutritive value, from a chemistry perspective, sugar is great. Sugar contributes to several functions in baked goods. Aside from the obvious taste, some of sugar’s functional properties in baked goods include its ability to tenderize a product, aid in preservation, and contribute to desirable browning.
Sugar as a tenderizer
Sugar is highly hygroscopic and is thus attracted to water. Sugar binds water by hydrogen bonds. Its affinity to water contributes to its tenderizing properties as it prevents the water from being used by other substances such as starch and protein. When making a product that desires a soft, delicate crumb, you want to minimize the production of gluten (protein) and reduce gelatinization (starch).
The proteins present in flour include gliadin (contributes to stickiness) and glutenin (contributes to elasticity). When flour is mixed with water, these two proteins will form gluten. Too much gluten formation will contribute to a rigid and tough dough/batter. The addition of sugar competes with proteins for water thus limiting the amount of gluten formation. However, in the right proportions, enough gluten is able to be formed in order to trap the gases produced by leavening agents and mixing which allows the batter to expand and rise during baking to produce the desired crumb texture.
Another component in flour is starch. Starch in the presence of water and heat will begin to swell (gelatinize) which results in the thickening of batters. If allowed to set, this thickened batter will form a gel with semi-solid characteristics. However, the addition of sugar will reduce gelatinization as sugar and starch will compete for water. Consequently, the point at which a cake will set (turn from a liquid state to a solid state) will be delayed allowing for leavening agents to work their magic and create gases that allow the batter to expand and produce a product with a soft, crumb texture.
Sugar as a preservative
Because of sugar’s hygroscopic nature, its ability to attract water lowers the water activity of food. Water activity is a measure of the amount of water available for microbial activity. Consequently, the presence of sugar binds water so it is no longer available for microbial activity, thus helping to preserve foods from microbial spoilage.
Sugar and browning
The brown surfaces on baked goods is a result of sugar undergoing Maillard browning. During the Maillard reaction, reducing sugars and amino acids in the present of heat go through a series of reactions to cause browning. The browning produced from this reaction contributes to the pleasant aromas and browned surfaces of many baked goods.
These are just some of the functional properties of sugar. Although, sugar may not be very nutritive, it plays a major functional purpose in baked goods. My aim, as I bake, is to limit the use of added sugars and to focus more on using naturally occurring sugar found in nature’s candy.. I mean fruit. In the worst case scenario, when it is just not possible, I’ll just have to remember to consume those baked goods in moderation.