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 function in foods, including sweetness, texture, color, flavor formation, freezing point depression, preservation, and fermentation. Some of the most important properties of sugar are outlined in this article.

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. All sugars do not have the same sweetness. Since their structure vary, 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 lever 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 breads, rice, pasta, and fruits, i.e., 4 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.

They are Readily Fermented By Microorganisms

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 is 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 breakdown 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 reach with proteins, especially at high heat to produce dark polymers in a process called Maillard browning.  

Maillard reaction and caramelization

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.

Courtney Simons
Administrator
Courtney Simons is a food science professor. He holds a BS degree in food science and a Ph.D. in cereal science from North Dakota State University.
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