In addition to providing a sweet taste and flavour, sugar performs a variety of functions in food products. Sugar is used as a preservative, where sugar inhibits the growth of microorganisms. Sugar is used in baked goods, like cakes, to hold moisture and prevent staleness that is noticed when these foods dry out. In canned fruit and vegetables, sugar enhances texture and colours. Sugar is also used to prevent large ice crystals from forming in frozen sweet mixtures, like ice cream, and to support fermentation in products containing yeast, such as bread. In these roles and others, sugar is an important and versatile food ingredient.
More functions of sugar in foods include:
Preserves and Jams
Sugar is commonly used as a preservative in jams and jellies, and enhances the colour and flavour of various fruits. The addition of sugars to jams and jellies is also essential to the gelling process, to obtain the desired consistency and firmness.
Sugar helps tenderize bakery products and provides a source of nourishment for the growth of yeast, which helps the leavening process (e.g. breads to rise). The browing reaction that sugar undergoes when exposed to heat adds flavour, and contributes to the appearance of colour that can be seen on baked goods such as the crusts of bread and the browning of cookies.
Canning and Freezing
Sugars are added to canned fruits and vegetables to improve flavour, enhance texture, and preserve natural colours. Sugars are also used to slow the freezing process, and prevent large ice crystals from forming in frozen sweet mixtures, such as ice cream. Large ice crystals can create a gritty texture, while the formation of smaller ice crystals results in a smoother product, providing a more desirable texture. Sugars also increase the thickness of frozen desserts, imparting a thick, creamy texture in the mouth.
Sugar (sucrose) is the primary ingredient in a wide variety of candies, largely due to its solubility. In its simplest form, candy is made by dissolving sugar in water, and heating the solution. As the temperature rises, more sugar can dissolve. The solution is boiled until no more sugar will dissolve (a "supersaturated" solution). As the solution continues to boil, the water evaporates, making the solution more concentrated. When the solution cools, the sugar's solubility decreases and the sugar crystallizes out of solution. The type of candy that is being made (and its desired consistency) determines the degree of sugar concentration, and the extent to which sugar particles are recrystallized.
Sugar is a key ingredient in the preparation of custards, puddings, and sauces. These food products depend on sugar to perform a number of functions, in addition to its role as a sweetener. In custards, sugars help to breakdown proteins in egg whites so that they are more evenly dispersed in the liquid mixture. This permits the egg mixture to thicken slowly, mixing with the other ingredients, resulting in a smoother consistency. Sugar helps to prevent lumping and thicken sauces and puddings by separating the starch molecules of the flour (or other thickening ingredient such as cornstarch). This allows for a more desirable consistency. In non-sweet foods such as salad dressings, condiments and sauces, sugars enhance flavours and balance the natural acidity of tomato and vinegar-based products. This is because sugars are easily broken down by weak acids.
Sugars are added to beverages to provide both sweetness and body (otherwise known as "mouthfeel"). Sugars are also important in the brewing and wine-making industry. Sugars or other carbohydrates (except lactose) can be used to produce alcohols by fermentation. During fermentation, yeast feeds on sugars and produces bubbles of carbon dioxide, water, and alcohol.
Sugar also has some surprising non-food uses:
sugar is involved in the fermentation process to make products containing alcohol (such as wine);
sugar slows the setting of cement and glues;
sugar is used to help make certain types of detergents;
sugar is used in the textile industry for sizing and finishing fabrics;
sugar is used to make certain pharmaceuticals;
sugar is used in wound healing.
To learn more, see our resources Sugar From Plant to Food and Facts on Sugars.