The importance and function of sugar in our food
Sugars have a number of important properties that contribute uniquely to a food’s appearance, texture and shelf life. Sugars help many foods to be more palatable, enhancing their flavour and mouthfeel. Sugars also helps foods to last longer, provide kilojoules, add viscosity and be used as a bulking agent.
Sugars are an important ingredient in both the food we make at home, and the manufactured foods we find on our supermarket shelves. Many people have concerns about the amount of sugar they consume and often look for low sugar or ‘healthy’ alternatives when shopping for food products.
Reducing or removing sugars from a product often requires replacing it with a number of substitute ingredients to achieve the same quality, taste and texture profile.
Sugar as a bulking agent – sugar contributes to the texture of many of the foods we enjoy. Sugar plays an important part as a bulking agent as not only does it affect the physical characteristic of food, but it adds bulk to many foods which in turn impacts on the texture and mouthfeel of many foods.
Sugar plays an important role in most baking applications as it helps to promote lightness in baked goods by interacting with leavening agents to create small air cells. Sugar helps to stop cookies and biscuits from obtaining surface cracking and helps give many cakes their lightness by interacting with egg proteins to help stabilise the whipped foam structure of the batter.
Sugar as a preservative – by acting as a humectant (maintaining and stabilising the water content in foods) sugar helps to prevent or slow the growth of bacteria, moulds and yeast in food like jam and preserves. It helps to prolong the shelf life of many foods on our supermarket shelves and is used extensively in home-based food preserving because of its preserving characteristics.
Sugar as a flavour enhancer – adding a little sugar to nutritious foods such as sour fruits (frozen berries or rhubarb), or to porridge, helps to balance the flavour and make them more palatable. Sugar also enhances fruit flavours in foods.
Sugar used for colour – upon heating, sugar breaks down to produce the colour and desirable flavour that characterises many cooked foods (think of the brown/caramel colour on the top of a Creme Brulee). This is caused by sugars reacting with proteins as they break down in the cooking process, and is called the Maillard reaction.
Many simple recipes use cooked sugar and there are several stages that give different results , for example thread, soft ball, firm ball, hard ball, soft crack, hard crack and caramel. Each of the stages of cooked sugar offers a gradually darker colour.
Sugar adds viscosity – viscosity is how thick, sticky, and semi-fluid a liquid is in terms of consistency. Sugar helps to provide a certain body or thickness in many types of drinks and in semi-liquid foods like syrups, chutneys and sweet sauces.
Sugar as an anticoagulant – when it’s heated, sugar delays the coagulation of proteins (or the change to a more semi-solid state), which is useful for products such as baked custards and other desserts.
Food and beverage manufacturers worldwide are looking for ways in which they can reduce the sugar content of their products in response to consumer demand. This often poses many technical barriers due to sugar’s role in providing more than just taste in the foods we consume. It usually results in a less ‘clean label’ as there is a longer list of ingredients needed to maintain the many different functions of sugar.
This complex combination of texture and taste that many consumers prefer makes the reduction or elimination of sugar more challenging than simply adding a non-nutritive sweetener into a product in place of sugar. Often this will result in less than preferred results in taste, mouthfeel and texture for many foods. Even a straight swap involves significant challenges in getting the appropriate flavour and stability for foods exposed to high temperatures.
Sugar provides bulk, density, and viscosity in food products. Removing or reducing sugars from high-sugar-containing products and replacing them with lower energy sweeteners requires that they are replaced by other molecules that can also control these physical changes in the product.
A variety of bulking agents such as insoluble fibres (gum systems) and polydextrose can be used, although these do not all reduce the energy content of the food (which is often the original intention of reducing sugar content).
Sugar, like salt, also reduces the water activity in foods and beverages, making water unavailable for use by bacteria and fungi, thereby reducing microbiological activity and mould formation. For this reason, many food and beverages containing high concentrations of sugars do not need to be refrigerated.
When sugar is removed from a product, or replaced with a non-nutritive sweetener, its preservative properties are lost, and it will therefore have a shorter shelf life. Preservatives may need to be added to these products, which is often less acceptable for consumers who are concerned about the quality and health aspects of the food they purchase.
In breakfast cereals, sugar often plays an important functional role other than taste. Small amounts of sugar provide lubrication for “dough” being processed into extruded breakfast cereal products. This means manufacturers can produce cereal products without having to rely on complex machinery systems or additional chemical compounds to help in the manufacturing process. Sugar is also used to help bind pressed and moulded cereal products such as Weetbix.
Simply removing sugar from many food products would necessitate the use of other, less “natural” compounds or ingredients in order to make the same product. Removing sugar entirely from many of the food products we consume would lead to shorter shelf life, a greater chance of contamination by mould or bacteria and so a food safety risk. There is a greater dependence on additives and other less ‘natural’ ingredients when compared to sugar. Some reduced sugar products can also be equal or higher in kilojoules to the original product. These factors may partly explain the difficulties faced by manufacturers when carrying out sugar reduction or replacement programs.
For more information on the role of sugar in food, see the infographic 'Why is sugar in my food'
Alexander, RJ. Sweeteners: Nutritive: practical Guides for the Food Industry. St. Paul, Minn: Eagan Pr; 1998.
Charley, H. Food science. New York: Wiley; 1982.