Nutrition Manager, External Affairs Division, SASA
With the increasing pressure to reduce the sugar body in foods, it is important to appreciate that sugar is very difficult to replace in food production. Sugar is one of the most basic structures in nature and, yet has the broadest area of use in food production. Sugar helps to ensure the high quality of our food. Without sugar, jam would spoil, ice cream would form crystals, and bread would dry out.
The most obvious function of sugar is to provide sweetness. Sugar has a uniquely clean sweetness that is entirely free from off taste or aftertaste. Breast milk, the first taste that we encounter is sweet, which is probably why a sweet taste is interpreted positively. Our inherent affinity for sweetness may also be explained by the fact that, in nature, sweet products are rarely poisonous, in contrast to many bitter substances.
Sugar can affect the weight and volume of food. Sugar increases the volume of bread because the yeast breaks down sugar and in the process produces carbon dioxide. Carbon dioxide increases the volume of the bread and makes it more soft and airy.
In cakes, sugar creates bulk. Trying to replace the sugar in these products is almost impossible – sugar is required to trap the air required to keep cakes spongy.
Sugar can give many food products an appetising colour. This may be through caramelisation, the Maillard reaction, or because sugar is able to preserve colour. A certain body of sugar, for instance, ensures that jams and marmalades retain their colour.
Small amounts of sugar can enhance tastes and aromas without making them taste sweet. For example, a small amount of added sugar can improve the taste of sour or bitter foods, such as tomato sauce. Sugar’s aroma-enhancing properties are used in a wide range of foods. A sprinkling of sugar can enhance the smell of cooked vegetables and meat.
Texture refers to sensation felt when food comes into contact with our fingers, tongue, palate, or teeth. Foods have different textures, such as crisp potato chips, a hard boiled sweet, crunchy green apples or a creamy ice cream. Sugar affects texture by providing volume and consistency in many products such as bread, jam and beverages. In bread making, sugar speeds up the fermentation process of the dough, giving it a more spongy structure. The manufacture of jam, marmalade and jelly is the fine art of balancing the right amounts of sugar and pectin to form a gel. Pectin is found in the cell walls of fruits and vegetables. Too little sugar will make the jam watery, causing the gelling process to fail while too much sugar may result in jam becoming hard and lumpy.
The preservative properties of sugar are used in foods such as jams, juices and pickles. Moulds, bacteria and other micro-organisms need water to survive and grow. When sugar is raised to a certain level, it binds to all the water around it. This reduces the amount of available water, thus inhibiting the growth of micro-organisms and increasing the shelf life of these food items. The same principle is used in baked goods and cereals to keep these foods fresh.
The shelf life of bread is extended because sugar causes water to be retained for longer.
In products such as biscuits and boiled sweets, which contain small amounts of water and large amounts of sugar, the relative moisture level is lower than the ambient humidity. Without protective packaging, these products will absorb moisture from the air and become soggy.