Sugars are the natural building blocks of carbohydrates. They can be found in fruits, vegetables, milk, and tree sap. The monosaccharides glucose, fructose, and galactose, as well as the disaccharides sucrose, lactose, and maltose, are the most frequent sugars present in foods. Sugars provide a variety of functions in foods, including sweetness, texture, color, flavor formation, freezing point depression, preservation, and fermentation. This article outlines some of the most important properties of sugar.
They Are Sweet
The most recognizable function of sugars is their sweetness. Sweetness is one of the five tastes, along with salty, bitter, sour, and umami. Not all sugars have the same sweetness. Since their structure varies, they bind to taste receptors differently and hence create differing perceptions as nerve signals are sent from the taste buds to the brain. Sweetness index is generally compared against sucrose (table sugar), which is given a value of 100. The sweetness of fructose is very high (173), while lactose is very low (16).
They Are Soluble in Water
The highly hydrophilic nature of sugars allows them to interact with and dissolve in water easily. The rate at which sugars dissolve can be increased by increasing temperature, agitation, and by reducing their particle size (grinding).
They Supply Energy
Sugar is a carbohydrate that contains the same amount of calories per gram as other carbohydrate sources such as bread, rice, pasta, and fruits, i.e., four calories of energy per gram. Carbohydrates are broken down into glucose in the process of glycolysis to make energy in the form of ATP to run various biochemical functions.
Microorganisms Readily Ferment Them
Fermentation is a metabolic process in which a carbohydrate, such as starch or sugar, is converted into byproducts, such as alcohol and acids, by a microorganism. Additional byproducts, e.g., carbon dioxide and flavor compounds generated during fermentation, are essential in enhancing the sensory quality of end products. Fermentation is applied in bread, beer, wine, and yogurt making.
They Preserve
Water is required for pathogenic microbes to grow. Sugar acts as a water-binding agent. This reduces the amount of water available to microorganisms for their growth and restricts the amount left for chemical reactions that may lead to food spoilage.
They Darken Foods
High heat causes sugars to break down into their constituent monosaccharides. On further heating, monosaccharides react with each other to form complex polymers and flavors. The polymers are generally dark in color, which may enhance the appearance of the food. We call this process caramelization. Sugars may also react with proteins, especially at high heat, to produce dark polymers in a process called Maillard browning.
Conclusion
Sugars are generally known for their sweetness, but they also play an important role in other functional properties of food, including nutrition, energy, fermentation, preservation, color, and flavor.
Reference: Potter, N. N., & Hotchkiss, J. H. (2012). Food science. Springer Science & Business Media.
