NUTRITION

FUNCTIONAL
PROPERTIES OF SUGAR


PRIYA SEETAL

Nutrition Manager, External Affairs Division, SASA



Sugar has important functional properties in food preparation and processing and is clearly shown on legally compliant food labels so you can be rest assured there is no so-called ‘hidden sugar’.




Why is sugar added to foods?

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.




Check the ingredients list


If you are unsure that table sugar has been added to the product that you have bought, all you need to do is check the ingredients list. If the word “sucrose” or “sugar” appears, then the food has sugar in it. All food products that carry a nutrition information table must also indicate the amount of sugar in the product. You can find out how much sugar is in the food under the section of the label that says “Glycaemic Carbohydrate (g)” or “Total Carbohydrates (g)”. In these sections, “total sugars (g)” will be indicated.







Sweet taste

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. 




Volume

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. 



Colour

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.




Taste and aroma

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

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. 




Shelf life

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.




Moisture retention

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.




Can foods be reformulated to contain less sugar?


Reducing the amount of sugar in food products has become popular and seen by many as the cure for obesity. However, sugar reduction or replacement is not straightforward and may result in unintended consequences. Sugar reduction can result in a poor quality product (try making biscuits with less or no sugar). 


Replacement of sugar with other ingredients is likely to require an increased number of additives that are not familiar. Some sugar free items contain more calories than their sugar containing counterparts. This is because fat, which contains twice the amount of calories per gram than sugar, is used in place of sugar to increase the volume required to make a quality product. There needs to be careful consideration of many factors before sugar is replaced in foods.







References:

  1. JM Cooper (2017). The challenges of reformulation for sugars reduction. The Journal of Food Science and Technology. (http://fstjournal.org/features/31-1/sugars-reduction) 
  2. Goldfein, K. R. and Slavin, J. L. (2015), Why Sugar is Added to Food: Food Science 101. Comprehensive Reviews in Food Science and Food Safety, 14: 644–656. doi:10.1111/1541-4337.12151
  3. Nordic Sugar http://www.nordicsugar.com/industry/on-a-technical-level/




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