Sucrose
Sucrose, commonly called table sugar, is a disaccharide composed of glucose and fructose. It is extracted commercially from sugarcane and sugar beet.[1] In plants, sucrose is a major means of transporting carbon from leaves to tissues that use it for growth or storage.[2]
Chemical structure
The two monosaccharide units are joined by a glycosidic bond between carbon 1 of glucose and carbon 2 of fructose. These are the anomeric carbon atoms of the two sugars. Because both are involved in the bond, sucrose is not a reducing sugar and does not undergo mutarotation.[1]
Hydrolysis splits sucrose into equal molecular amounts of glucose and fructose. The resulting mixture is called invert sugar because its optical rotation has the opposite sign to that of sucrose. Invertase enzymes catalyse this reaction.[1]
Role in plants
Sucrose moves over long distances through the phloem, the plant's sugar-transporting tissue. Mature leaves supply sucrose made from carbon fixed by photosynthesis. Growing tissues and storage organs receive it; these receiving parts are termed sinks. Export depends on photosynthesis and the carbon retained as starch or stored temporarily in vacuoles.[2]
Movement of the sap is explained by a pressure difference between source and sink. Once delivered, sucrose can be used in metabolism, converted into stored starch or taken into vacuoles. Supply and demand change with development and environmental conditions.[2]
Extraction and concentration
Traditional cane-sugar manufacture involved pressing the stalks to release juice, then evaporating water to concentrate it. The concentrated liquid was cooled to obtain sugar crystals. As water is removed, the solution's boiling point rises, so a progressively more concentrated solution requires a higher temperature to boil at the same pressure.[3]
The multiple-effect evaporator, developed in the nineteenth century, reused heat from vapour leaving one vessel to heat the next. Reducing pressure in the vessels also lowered the boiling temperature. These changes reduced the fuel needed for concentration and helped make sugar production more efficient.[3]
Culinary forms
White granulated sugar is almost pure sucrose. Brown sugar contains molasses, which contributes other sugars and affects flavour. Both attract moisture; their effects on dough depend on the other ingredients and mixing method.[4]
See also
References
- ↑ 1.0 1.1 1.2 McMurry, John (2023-09-20). "25.8 Disaccharides". Organic Chemistry. OpenStax. Retrieved 2026-10-13.
glucose and 1 equivalent of fructose on hydrolysis
- ↑ 2.0 2.1 2.2 Lemoine, Remi; et al. (2013-07-24). "Source-to-sink transport of sugar and regulation by environmental factors". Frontiers in Plant Science. 4: 272. doi:10.3389/fpls.2013.00272. Retrieved 2026-10-13.
hydrostatic pressure difference
- ↑ 3.0 3.1 Melhado, William (2022-12-01). "Sugar: 'White Gold' Transforming America". ChemMatters. American Chemical Society. Retrieved 2026-10-13.
concentrated by evaporating the water
- ↑ Parks, Stella (2024-01-05). "Cookie Science: The Real Differences Between Brown and White Sugars". Serious Eats. Retrieved 2026-10-13.
White granulated sugar is 99% pure sucrose
Attribution
Adapted from English Wikipedia's Sucrose, revision 1379002587 (contributors and history), under the Creative Commons Attribution-ShareAlike 4.0 licence. The prose has been rewritten and condensed, and the references replaced with independently checked sources.